Breach of contract

I have been a customer for many years, last year I took out a data contract with Telkom Mobile. On the contract I signed I specified the amount that should be debited from my bank account. At the time of sale I also expressly informed the agent that this is the debit order mandate that I authorise and it should not exceed this amount (the amount being the amount of the contract only). In August I called in to lay a complaint as I noticed my bill was sitting at R500, the agent Thabiso ( ********** 7) was useless. I received no follow up call for my complaint even though I was told I will get feedback within 72 hours. When calling back another lady answered saying they tried to call me and they can't help me because I had to call in and set a maximum spend limit because these are Telkom's rules. I went to the Telkom store on a Friday afternoon, a few weeks later and they requested someone call me, I expressly told Nokwabe (I think that was her name) to get her manager to call me back on the Monday because she told me that no manager/supervisor worked over the weekend. I waited till Wednesday however I received no call. I call Telkom directly and spoke to the Compliance Officer who said she would pass on my complaint and to date I still have not been called back. The most frustrating part is that everyone seems to tell me that I needed to call in to restrict my data line because they aren't able to set it at time of sale. This rule that everyone keeps referring to only became effective in November last year, the data contract was taken out in July when the rule was not effective and neither does it state on this particular contract that a spend limit is set at R500. As mentioned before I have been a customer with Telkom for years and I still hold (ALL) signed contracts that I received at time of sale. So I am honestly tired of hearing this sad excuse you guys are using, this needs to be fixed and I should not be debited this extra R500 that I did not authorised at the time of signing the contract!!!!