Closure of account - delays !

Closure of account with Discovery Credit card, due to bad service I have closed my acc. I have a credit balance and have been chasing to get this amount paid for more than 1 month. Every time I call they advise 5 - 7 working days, which is long over. They even promise to call me back and they don't. I am requesting for someone at Discovery to advise when a small amount of money of R5500 will be paid?