Telkom Unfair treatment

I have a month to month LET data contact with Telkom, I was late on my September payment, my account was then suspended I then paid the amount I owned to them, then later in the month they went into my account on a day we had not agree on and took money from it, ok fine now today 30 of November again they came into my bank account and took money but this time it was more than what we agreed on, when I ask they tell me that 138% extra they took from my account is because of my late payment in September so it is penalties when I ask why the penalties are 138% of my monthly installment I was told this how it's like, but the agreement I have with Telkom is that I will be charged about 21% of my monthly installment as penalties. I then ask for the agreement I initialed and signed which I was promised an electronic copy and never got,but they say they don't do that I needed to go to the store I sign the agreement at, and that store is now 1000 km from where I relocated to which is absolutely ridiculous