Home Fiber Cancellation

I have MTN home fiber. It has been giving me problems for a month, line is slow. Where I could run multiple devises, I can barely run one. For the last week I have been trying to get through to technical support and it just rings same goes for accounts. I have held on for more than 20 min and it just rings. The service is useless to say the least. I need someone to assist in cancelling my service ASAP seeing that I can't get through to anyone.