Incorrect Billing

This is the 3rd month of incorrect billing on my 4 mobile accounts! No point in phoning, because I get transferred from one department to the next. Customer service says it's accounts, accounts says it's contracts, contracts says it's accounts, and they say again that any of the customer service agents can help me sort it out!! Dec I paid over R900. I was told it's due to the overlapping of going onto my new contract, and my new benefits kicked in early, so I'm paying extra for that. End of Jan and end of Feb I paid R694.01 for 4 X R139 Top-Up contracts. Each time your agents tries to find valid excuses, while the contracts department confirmed my 4 contracts are indeed approved for only R139 each. (on the account details you can see that my old 2 contracts are still billed for R208 instead of R139) I would like this to be rectified asap, with the refund sent to my account. If this is not sorted out, I will cancel my contracts when I get my bonus in June. Alternatively I will simply not renew my next contracts with you. Can someone please investigate this properly and sort it out. Every sent counts. I cannot simply continue paying R208 for an approved R139 contract!!