Other party trying to defraud more money

I have been served a legal notice to pay back some amount for which I signed a MoU at one time and gave a signed cheque for the same. However, the other party did not wait for the agreed upon time and tried to encash the cheque previously given. The cheque got bounced due to mismatch of signature. It happened more than a year ago. Now, I have paid half of the amount but did not have any receipt of the same (I do have eye-witnesses though who would testify in court). I am ready to pay the remaining amount now at a condition of the other party to give me a receipt of the full amount to settle all dues. However, the other party (who sent the legal notice) is not ready to sign any legally valid receipt and is saying that he may sign on some random paper accepting receipt of the full amount. I am afraid that after paying the remaining amount, the other party would send another legal notice asking for the payment again since the random receipt would not be legally valid. What should I do ?