Accounts incompetency

I cancelled my fiber with Telkom in June 2024. This seemingly confused their accounts department, who charged me an additional amount of R 1600.00. When contacting Telkom they agreed that this was a mistake and promised me a refund within 30 days. I had to e mail them bank statements, to prove that they did indeed deduct the money incorrectly, I have been through this process three times and every time I'm told the money will be paid within 30 days. My Telkom statement is religiously e mailed to me every month showing a credit of R 1600.00. I have given up trying to retrieve my money.