Worst service and incorrect billing

I have had a contract with telkom for 6 years +. It was all going well untill I renewed my contract in May 2017. I signed for a contact of R479 per month. Every month after that I was billed for way more than what I actually used, yes I did buy data but on the invoice for what I was being charged for came nowhere near to what came off my account each month. I logged many disputes on the invoices and had no luck. No one phoned me back to find out what the issue is. In November 2017 I get my invoice and it is in credit of - R7800. 00. So I phoned them again to ask what is going on. They told me that they have over charged me the past few months and now I am in credit which I has happy about. In December I received my invoice and it was R386. 00 which came off the credit. In January 2018 I received my invoice for R1800 and the credit is gone. I phoned them AGAIN to find out why the credit was removed and they told me they had put it into the wrong account which I argued about. So in Feb they I get another invoice for R1300, but this time I stopped the debit order before it came off. So 2 days after the debit order was supposed to go off, my cell phone number was completely suspended and switched off. Could not make or receive calls. I phoned them on the Thursday morning to ask them what are they gonna do about it. They intern told me to pay the R1300 for it to be switched on. I told them once again to go back on my account and look how much they have charged me the past few months and that I was credited and then it was removed. The lady said she would get back to me shortly on another number that I had issued her with. I had no feed back that whole day. I phoned once again on Friday, only to be told I don't have an account with telkom and my contact has been canceled. So this is where I am confused, I never signed a cancelation form nor did I ask them to cancel my contract. So the lady logs a case. I have phoned every week for tbe past 3 weeks and nothing has been done. 1st to try and get hold of telkom is a mission. On hold for 10 minutes + and they maybe answer then each time I have to explain the whole problem once again even though I have a case number. So I received my March invoice and it is R5800. 00 for a termination of contract which I did not ask for. I have tried to contact you telkom and a I'm still waiting for you to contact me to sort this out. This is the worst service ever.