Telkom service

I have a Telkom mobile account and after more than 20 phone calls still nothing resolved. They are unable to give ne a copy of my contract and suddenly receive a increased bill and I want to know who aithorised the limit increase and nobody can give me answers. A manager phoned me Tuesday he send for investigation and now he is nowhere to be found. Their service is pathetic and I will not pay the bill unril they can proof who increased the limit.