Pathetic service RCS

So I received my statement on the 12/11/19 that showed my balance, on the 02/12/19 I overpay. In the same week I get an sms that I still have an outstanding balance on my account. Morning of the 9/12/19 I call the contact center all that was done by Abigail (got through to her twice) Yongama or Yondela and Sivu was transfer me. While listening to the pathetic music I still get through to agents that tell me they cannot assist me. This is by far the most unpleasant call experience I've ever had with RCS cards and I wonder if my query will be resolved as I cannot understand why I still have a balance on my account when I overpaid. All the above mentioned agents took my ID number but none of them could get my details on their system and none of them called me as I will assume after getting an irate client you want to get back to them with correct information.