How to complain about your card machine provider, and when to escalate to the Ombudsman

Most merchants complain the way they would to a restaurant: a cross phone call, a promise that someone will look into it, then nothing. Card machine providers are financial firms, and financial firms run on formal complaints processes with regulated deadlines. Use the process and you get a dated paper trail, a forced decision, and a free referee if the answer is wrong. Skip it and you are just a voice in a call queue. This guide walks through the process in order, with a letter you can copy, and is honest about the cases where complaining is the wrong tool and leaving is the right one.

Step 1: Work out what you are actually asking for

A complaint that says “your service is terrible” gets a sympathy paragraph. A complaint that says “you charged £29.50 in March for a minimum monthly service charge that is not in my contract, refund it” gets a decision. Before you write anything, pin down three things: what happened (with dates and amounts), what it cost you, and what you want the provider to do about it. Common asks that succeed: refund of a fee not in the contract, release of held settlement funds, correction of a rate applied wrongly, waiver of a charge the provider caused (for example a late equipment return fee when their courier never came), and written confirmation of something they keep promising verbally.

Step 2: Complain in writing, to the right place

Every FCA-regulated provider must publish a complaints procedure. Search the provider name plus “complaints procedure” and use the exact channel they list, because a complaint sent to the sales inbox can genuinely sit unread. Worldpay, for example, takes complaints at complaints@worldpay.com. For other providers, check the complaints page on their own website rather than trusting an address from a forum post; addresses change and a misdirected complaint does not start the clock. Whatever the channel, put the word “complaint” in the subject line or first sentence, because that is the word that obliges the firm to log it formally.

Complaint letter template

[Your Business Name] [Your Address] [Date] [Provider name] [Complaints address from their published complaints procedure] Dear Sir or Madam, FORMAL COMPLAINT Merchant ID: [YOUR MERCHANT ID] Account name: [YOUR BUSINESS NAME] I am making a formal complaint about my merchant services account. What happened: [One or two sentences. For example: on 3 March 2026 you debited £29.50 described as a minimum monthly service charge. This charge does not appear in my agreement dated 12 May 2024.] What it has cost me: [Amounts and dates. Attach statements if you have them.] What I am asking you to do: [For example: refund the £29.50, confirm the charge will not recur, and send me written confirmation.] Please acknowledge this complaint and provide your final response within the timescales required by the FCA. If I do not receive a satisfactory final response, I will refer this complaint to the Financial Ombudsman Service. Yours faithfully, [Your Name] [Position, e.g. Owner]

Keep a copy, note the date you sent it, and if you post it use recorded delivery. If the provider phones you to discuss it, take notes and confirm anything agreed by email afterwards. You are building the file the Ombudsman would read.

Step 3: The deadlines that now apply to the provider

Once a regulated firm receives your complaint, the FCA’s rules put it on a clock, as of August 2026:

• Payment-services complaints (most complaints about a merchant account: settlement, held funds, charges for processing) require a final response within 15 business days, extendable to 35 business days in exceptional circumstances, with an explanation for the delay.
• Everything else falls under the general rule: a final response by the end of 8 weeks from receipt.
• The final response must tell you about your right to go to the Financial Ombudsman Service and the 6-month time limit for doing so.

The practical rule of thumb: if 8 weeks pass and you have no final response, you do not have to keep waiting. That silence alone gives you the right to escalate.

Step 4: Escalate to the Financial Ombudsman Service

The Financial Ombudsman Service is a free, independent adjudicator, and it is not just for consumers. As of August 2026, two categories of business can use it:

• Micro-enterprises: fewer than 10 employees and annual turnover or annual balance sheet total of 2 million euros or less.
• Small businesses (eligible since 1 April 2019): annual turnover below £6.5 million, and either fewer than 50 employees or an annual balance sheet total below £5 million.

That covers the overwhelming majority of shops, cafes, salons, trades and single-site hospitality businesses reading this page. The provider also needs to be FCA-regulated, which acquirers and payment institutions are; if you deal with a sales intermediary rather than the acquirer directly, check whose name is on your merchant agreement and complain to the firm that actually holds the regulated relationship, as well as the intermediary if it caused the problem.

You can refer your complaint to the FOS once you have a final response you disagree with, or once the response deadline has passed with no final response. Three time limits apply, as of August 2026: refer within 6 months of the final response, and the underlying event must generally be within 6 years, or within 3 years of when you knew or reasonably should have known you had cause to complain, whichever is later. Referring is free, you do not need a lawyer, and the firm cannot charge you for it or punish you for doing it.

What compensation actually looks like

Be realistic going in. The Ombudsman’s job is to put you back in the position you should have been in, not to punish the provider. In practice, for merchant services complaints, that tends to mean money wrongly taken is refunded, sometimes with interest; funds wrongly held are released; charges that were never agreed are removed going forward; and where the firm’s handling caused real inconvenience, a modest additional award on top. If the provider’s failure caused a measurable business loss, evidence it carefully with dates and figures, because vague claims of lost trade carry little weight and documented ones carry a lot. This is another reason the written record from Step 2 matters.

Complain or leave? Honest answer: it depends what is broken

A complaint is a tool for recovering something you are owed. It is a poor tool for escaping a deal you no longer want. Two quick tests:

Complain when there is a specific wrong with a specific remedy: a fee not in your contract, money held without explanation, a promised rate never applied, equipment charges for kit you returned. These are exactly the cases the process exists for, and they often resolve at Step 2 because the provider can see where a formal complaint ends up.

Leavewhen the real problem is the deal itself: the rate is uncompetitive, the monthly fees have crept up, the support is chronically slow. No ombudsman will rewrite a lawful contract into a better one, and every month spent complaining about a bad deal is a month still paying for it. Here is the arithmetic that focuses the mind: if you are overpaying by £40 a month and you spend the full 8-week response window plus a few months of FOS queue fighting about it, six months is £40 × 6 = £240 gone even if you eventually win the original point. Serving notice, or switching with the exit fee covered, stops the bleeding immediately. Our guide to getting out of a card machine contract covers notice periods, exit fees and the escape routes, and the two approaches are not exclusive: you can pursue a complaint for what you are owed while your notice period runs.

Frequently asked questions

Related reading

• How to get out of a card machine contract
• Hidden card machine fees: the full list
• Card machine money not in your bank? Settlement delays and holds
• Card machine fees suddenly increased? What to do
• Chargebacks for UK merchants: the full guide