Bad service on contract

On numerous occasions I have had problems with increased spend limits. On numerous occassions I have ask agents not to increase my limit at any given time. I found that it was once again increase without my consent, how s this possible. I phoned the call centre again today and the lady advised me that if you receive a sms stating that your account has been increased that you should phone in and cancel. First of all, how can telkom increase your limit without your consent, secondly none of the other idiot call centre agents explained this to me on previous occasions, and if I asked at the beginning of a contact just to pay a fixed amount each month and sighned for it who gives telkom the right to increase or break that agreement. Furthermore I tried to contact Telkom via internet but was unsuccessful. I want to cancel my contract with them as I had to many bad experiences. I would not advise anyone to take out a contract with Telkom. I asked their agent today to put me through to complaints department and she answered that they don't have one I should go online. Bull man