telkom mobile provides a terrible service

I recently signed a contract with telkom mobile and received awful service from this branch after complaining on hello peter only then did they contact me and resolve my issue now a month later after signing a contract that is capped at R399 telkom sends me an sms to state that they will be debiting R676.90 from my account and I try calling them and theres continuesly no answer does anyone even work there during the day I went as far as getting the store managers cell number from the malls centre management I then called the store managers cell she said she could not hear me clearly and would call me back and never did what am I supposed to do I am not the first person that has issues with this store they are ******* and unfriendly and so unhelpful I signed a contract for a set amount and now they want to just deduct their own amounts this is not right and you cant even query because they don't answer absolutely pathetic service.