Bad Service

I have two contracts with MTN, one is an open line and there other is supposed to be a top up contract. every time I phone the call centre I get a different story as to why I am being billed ridiculous amounts. I had a call limit on the open line and when I enquired as to why I am paying more I could not get hold of them for a month, I sent numerous e-mails and the responses I got were not at all helpful and eventually was told that I did not have a call limit since 2014 but I have proof that I had a call limit, their agents are argumentative and the general response is ? don't know. both of my cell phones have not been able to make outgoing calls since last week Friday, this is since I asked the agent to reinstate the call limit and remove the call limit from the top up contract as the top up contract does not need a call limit, then I phoned again and the guy on the line was very disrespectful and every time I asked him why there is a call limit on a top up contract he tried to explain that I need to have a credit limit even if it is a top up contract. yesterday I phoned again and was told that the \top up contract"is an open line so can you please make up your mind???"""