Well here's the answer then, they made a mistake, which they have admitted, by entering €800 twice. They probably then got totally confused because some money was paid by cash and some by cheque. No proper accounting was done that day because, 1, they were too busy or, 2, the person doing the accounts didn't know what they were doing at the time.They may have been distracted as to what they were doing at the till.You have a receipt to say you paid in full, so no, dont pay another €400,€800 or whatever. Not your fault, theirs. end of story. So what if it's a small town, I know what small towns are like, do not let them bully you into paying just because you are new in town.!!!