Dedicated Sales consultant

We have over 20 business contracts with MTN and they still can not give me a dedicated sales person to sort out my account. Then when you actually dial the land line number *** no body answers the phone you hold until your phone cuts off. I find this very poor service is what us South Africans have to pay top dollar for is unacceptable. How do you actually get hold of anyone who really cares about their customers. We have been asking since January for assistance on our account maybe if we stop paying we will get some service. **** poor service there is no other words to describe the lack of interest MTN is showcasing.