Paul Moscardini, who runs Mason House Stores in Wetherby, West Yorkshire, had a frustrating week of watching his PayZone service collapse bit by bit. First the Chip and PIN function went, then it stopped taking top-ups. Finally, the whole thing went down. Each time he reported the problem to PayZone's premium rate line.

When he got past the 'Sorry, we're experiencing a high volume of calls' message, he would register the fault, reinforced by email. No response. Finally, the NFRN (which negotiated his deal with PayZone) intervened and a technical support bloke at PayZone got him up and running.

"It would appear they had attempted to do an upgrade to speed up those machines which do both Chip and PIN and top-up functions," says Paul, "but they should have disabled the Chip and PIN first. They admitted to fixing those who screamed loudest first."

The upshot was Paul lost £1,000 in shop sales for the week. PayZone offered him £30 compensation.

PayZone's press office said it was not aware of widespread problems, but Paul thinks otherwise.