Nedbank transfers money to a non existant account

Nedbank transfers a matured investment to the incorrect account. The correct account number is on the signed form but Nedbank are experts in getting it wrong. They transferred the matured investment to an incorrect account which does not exist and the money is now in a suspense account with the client loosing interest every day and they want my 100 year old mother to go back to the branch after sitting there for an hour when she gave the instruction. Interest will be claimed until the money goes into the correct account.If they want anything signed they must go to the 100 years old client who is more astute than many people