SolvedRM5164 | Over-repayments: The payable order has not been cashed
From HM Revenue & Customs · Repayment Claims Manual
If the payable order has not been cashed
send an explanation and an apology to the claimant
ask the claimant to return the payable order if it has not already been cashed
put the file on special B/F for 10 days to await a reply
If the claimant does not reply within 10 days report the facts to FAO (Payments)