No refund, terrible customer services

I had a contract with Telkom that expired in April. The last debit order debited more amount than what was owed. I logged a call for refund and credit bureau updates: ********** 2. This call was closed with the issue unresolved. I have escalated the issue multiple times without success. I have sent banks statements to ********** as part of another escalation, still not resolved. How many hoops should we jump through to get a refund?