WORST HOME INTERNET CONTRACT EVER!!!!!

I have had the most frustrating experience with MTN home internet. I decided to cancel my contract because the internet would end halfway through the month and it was completely frustrating. Now it has been four months and they refuse to let me cancel the contract even though I have done everything right on my side. I have returned the router and haven't had internet from them but I still am getting charged. now they are saying that my account is in arrears and no one will help me fix this. I hate this company and i hope no one ever chooses them as an internet provider. I am completely discussed with their service and the amount of my time that they have wasted.