Poorest service ever!

I am a customer at MTN for more than 10years and I am appalled at their customer service. There are no consultants to speak to when you call and they keep blocking my line even though I pay all my bills on time. They now insist that I owe them R2700 yet my monthly bill is R681 and I have sent proof that all has been paid up to date. I cannot wait for the contract to end so that I can leave and take my business to another company who will give me the customer service experience I expect and treat my queries with a sense of urgency. I have been to store in Centurion 3times now in a space of 2weeks with no positive feedback and my issue is still not resolved. Sometimes being loyal to a company does not mean that they will be loyal to you and Mtn just proves that.