Standard Bank will not allocate payment made

My husband closed his credit card account with Standard Bank, there was a small amount owing which should have been taken care of through a debit order set up. This didn't happen which we were unaware of, eventually the lawyers of Norman, Bisset and Associates got hold of him and he sorted out the outstanding immediately. Proof of payment was sent, so thinking all was sorted he app**** for a business overdraft at another bank a month later only to be told that it was declined due to bad credit at Standard Bank. The payment was made on the 16th April, it is now the 29th June and the payment is still not allocated. When we phone we get put through to numerous people and then get told we have to phone the lawyers, when we phone the lawyers they say it's out of their hands and we have to phone Standard Bank. This is impacting on our business, and after emailing the proof of payment numerous times as well as trying to sort it out over the phone, no one has done anything about it and they can't tell us why this has not been sorted.