Conplaint about a contract

I am so disappointed by Telkom. I have been having a contract with them for the past 6 years and the treatment i got from them is so disappointing. I went to a Telkom store in Maponya like 3 months ago to change banking details on.my contract because I had discontinued using the account they were debiting money from. Okay fine they told me that the money will be debited from the new account the following month. And that was not the case. Instead they debited on the old account then the debit order bounced became obviously the account didn't have money. What upsets me is that i had to pay the errears as if it was my fault that they didn't update the details. Same thing happened again this month, they still hadn't updated the details. Now i have to pay the arrears again! As if it was my fault!. Secondly. I have 3 phones under my contract which come from 2 different bank accounts. I took 2 insurances which were supposed to be debited on different account. I don't know what they did but they happened to switch the insurances and debit each from a wrong bank account. I had been calling and going to Telkom stores pleading with them to fix this mess. Till this day, no one was able to help me. I am so disappointed!!!!! If it was up to me i would actually close this contract because wow, their service is just rediculous!!!!