Good practical advice here: one legal point. Before he told you that he had overpaid you, while you were oblivious to the alleged overpayment, and in good faith kept the money as your own; did you make any purchases, any payments, on the basis that you had a certain bank account balance, that you would NOT have made in any event (so not ordinary bills, but (say) something special, for the new kid, or the wife)? If so, and insofar as the solicitor is claiming money paid out in mistake, then you can DEDUCT the amount of such PURCHASES MADE IN RELIANCE ON YOUR ALLEGED ENRICHMENT. You

Hi there, a friend asked me to look up the law on a very similar problem; this is what I concluded: The only way that the fine (in his case 85 quid) was payable, was if: (i) He had agreed to pay it (that is, he contracted to pay 85 pounds if he stayed beyond the maximum stay). In this case the English contract law rule on penalties would apply so that the fine was unenforceable. Note that there are other arguments too- about notice, and onerous terms. I also thought that the Unfair Terms in Consumer contracts Regulation might apply, on the basis that paying 85 pounds for staying 20 m