Treated unfairly

The worst experience in my life. In November 2016 I cancelled my connection then in December I got a text that they debited my account n I reversed it then never had of them again til in may when I wanted to check my account my hopefully I reconnect my services after that call I started getting messages that owe 800 and something I was assured my account is clear and I don't have to pay anything as I cancelled my account. I called and I assured they will escalate this and I will get feedback in 24 hours a month passes nothing from them i finally spoke to someone else stayed over an hour on the call and concluded they have escalated this. Now recently I have been receiving calls from debt collectors and my query was not even resolved. I went to my bank and went through the statement as I feared for my credit rating report. Only to find the text was sent in error and I reversed my November debit order and I don't knowhow that happened. I am so disappointed I was never advised of this til in may when I called them and I was accused of not making payments. Right now despite many attempts to get a solution with multi choice.dstv I don't what is happening with my account I am so hurt i was contacted by a manager asked her to contact me back as I was at work and didn't have my statement with me I have never received the call back or email anything of acknowledgement. I need help in feel they taking advantage of a young woman paying what was reversed In an error they caused it is not a problem. Please help me