Telkom is a ****

I have a very bad experience with telkomSa these guys have been terrorizing me for the past 4 months, I had a cellphone insurance which they debited R83,83 a month missed one payment they came back to debit R166, that was fine, the following month they came back to Debit R366 there was no funds in my account they tried Debiting on the 20 and our initial agreement was on the 31st spoke to one of their consultants in the phone and she told me that when you owe telkom they can debit at any time, first of all who charges over a R100 for an unpaid debit order Mtn charges R11,50 why are they charging that much because that's over the amount that I'm supposed to be paying. To top it all off my bank charges R147 for each failed debit order and when I ask them to block these people they can't, I don't want to change accounts but these telkom people are taking advantage because they can. They've now handed over my account to collectors and they provided them with my banking details, can someone assist I'd like to sue telkom because that is against the law, they are supposed to contact me to make an arrangement not just come into my personal account. Telkom has cost over R1500 in bank charges