MTN is not coming back to me!!!

I have a contract that is due for upgrade with MTN. go into store and they immediately tell me there is nothing they can do i must call the call centre. In a nutshell i would like to remain on the current contract im on and get the phone of my choice. Now being a loyal MTN customer i figured this wouldn't be an issue but it has become very clear that mtn could not be bothered. i have called the contact centre and was given BOGUS reference numbers for a manager call back in the retention's department this after being pushed from pillar to post. So i resorted to social media hoping that this would get the attention of MTN as i would like to sort this out, but ALAS true to the DISGUSTING level of customer service mtn provides no one from mtn has followed up with a call after asking me whats wrong.. I have since kept updating the post but NOPE MTN could not be bothered. I am extremely upset and i want to know what my rights are!!! do we live in a world where huge companies are allowed to neglect their customers in this manner?? i refuse to be ignored especially since im paying for a service . Can someone please assist as im at the line and actually had enough of MTN..