The loan amount in the purchase contract is wrong, but the mortgage has been repaid for five years. You can ask the buyers and sellers to re-sign the sales contract and modify the loan amount. According to the relevant public information, if the loan amount in the purchase contract is wrong, but the mortgage has been paid for five years, then the parties can re-sign the sales contract to buy and sell the house and modify the loan amount. In the process of buying and selling, if problems are found, try to solve them in time to reduce risks and losses.