POOR SERVICE FROM MTN

I've had ENOUGH!! I've never had a problem with MTN before, except these last two months. I kept on receiving sms's saying that I owe them. I paid the exact amount as per sms, and they continued switching off my network and reporting me as a slow payer. I also send them various proof of payments for them to clear my account. I am fed up, I feel like ending my contract with them at this point as their customer service is terrible!!