Absa silver credit. Payment wrong. Money owed to me by absa

Years ago I had a absa silver credit card. Fell behind due to being retrenched. Finally got the payments up to date. Account was at absa legal by then. Account was closed and I have forgotten about it. Got a letter from absa legal to say that payments was wrong and they now owe me money. Very good news. But now after some time, due to moving. I never got the letter in time. Now absa is saying there is no funds.