I have been reading stuff but not quite sure as to what to read or where to start. there is just so much information. Any payments we have made since to anyone we have since kept proof of payment and will do so for a very long time and so far so good with the rest of the debts. Just this one keeps cropping up like a bad aftertaste

hello, I was wondering if anyone would be able to give me any help or advice. My boyfriend received a letter today from tocatto ltd stating he owes £37.91 outstanding balance from a 3 mobile contract phone he had 5 years ago. 4 years ago this debt went to a Debt collection agency, I think it was moorecroft I cant quite remember, and he agreed to pay £10 a fortnight until it was paid. This debt was paid as I myself went to the royal bank of Scotland and paid the £10 a fortnight until it was all paid. About 2 years later we were sorting through paper work and thought we would no longer need the payment receipts from this debt so decided to throw them away. A year later , about this time last year, we received a letter from another DCA informing my boyfriend he still owed the outstanding £37.91. He phoned them and told them that he had paid the debt to which they asked for proof of payment. When he told them he had non as the receipts had been thrown away they told him as far as they were concerned without any proof of payment the debt was still owed. The person he spoke to was very rude and unhelpful and didn't give a damn and kept insisting he must pay. My boyfriend quite bluntly told them that they would not receive any money from him as the debt was already paid. The conversation kept going round in circles eventually the guy from the DCA put the phone down on him. We received another couple of letters and each time he phoned the company and told them the same thing. The debt has been paid and they will not get any money. Again they told him without proof then he still owes it. After about the 3rd letter we never heard from them again or any other DCA concerning this account until today. My partner hasn't rang Tocatto yet and we will probably hear the same cock and bull story from them. So I was wondering if anyone had any ideas how to get rid of them once and for all without having the pay the debt a second time. Any help would be very much appreciated Thx in advance Bec