Charged addistional despite request to cap account

I have numerous times called Telkom mobile and asked that my account be capped. Last month i was charged additional money as once again Telkom did not listen. I phoned in February and queried this. One NEVER hears results of queries raised to Telkom. They were once again instructed to cap my account. Despite the dispute of additional cost on my account, the instruction to cap my account, i once again got a sms from Telkom they have increased my capped amount. WHAT MUST I DO TO RESOLVE DISPUTE AND TO GET YOU TELKOM TO LISTEN-GO TO OTHER SERVICE PROVIDER?????