Worst service ever! Another mistake from Cell C accounts department!

Cell C has AGAIN messed up my account. Now that they've figured out their mistake, they started sending threatening texts that they will suspend my services if it is not paid immediately. I've paid every single invoice in full - have never missed a payment. The mistake was on THEIR side. I've spent numerous hours on the phone, but no one at Cell C is capable to rectify their problem. Now they expect me to dock up an pay a "debit note" which no one at Cell C is able to tell me what it is for. Worst service ever!!! Every time I phone customer service, I have to go through the whole story again, because the previous person did not log the complaint / query correctly. I never get any feedback and when I phone again, the previous query was closed on their side, without any feedback. Unacceptable! I can't go through this every two months. Is Cell C that desperate that they are willing to ***** from their customers? Get your services in order, or release me from my contract - which has been a nightmare from day one.