The £40-a-month fee for not filling in a form

The regulator-mandated summary box on this statement shows a 0.31% consumer debit rate, which sounds like one of the cheapest deals in this series. Then you look at the basket: £7.06 on average, 8,657 times a month. At that size, the 3p per-item fee is 0.42% of a typical sale and the 1p authorisation fee is another 0.14% - so the fixed pence add 0.57 points to a 0.31 point headline. The percentage on the summary page is a minority of the real price.

Then there is the line that should embarrass everyone involved: a £40.00 PCI non-compliance fee, charged monthly, alongside £2.50 plus VAT for "Secured PCI". That is roughly £480 a year billed because a security self-assessment questionnaire has not been completed - a form. It sits on top of the £21.25 monthly PCI DSS service fee the contract already carries.

The month's total: £621.63 of fees on £61,117.12 of card sales, an effective 1.02% before VAT, against a trailing twelve-month figure of 0.95% printed on the statement itself. And still the flat-rate comparison defends the acquirer: at SumUp's 1.69%, the same month costs £1,032.88. High-volume, tiny-ticket retail is exactly where per-item acquirer pricing earns its keep - once the avoidable lines are removed.