Unhappy Telkom Customer

It all started end of April when they did not debit what was due to the and they claimed that there was insufficient funds which I disputed and proved to the that there was more than enough money to debit for the rest of the year. Every time I call them when they suspend my services they would claim that I owe them penalties for the problem that was caused by them which I always dispute, but it seems to be going on monthly and I cannot be calling them every month it's tiring. My monthly invoice comes to me every month saying I own more than R900 which is incorrect because my monthly payment is R359 and I don't know where the R900 comes from. This tells me that after every call I make they don't clear what they initial said I owed as penalties they keep billing on top of it. The fact that no one can actually do something permanent about the issue when you call tell me that either people are not doing their job or there is something wrong about how Telkom does business.