Dissatisfaction about MTN upgrade and sales team

I have a contract with MTN i called them to do an upgrade on the 2nd . I made a follow up today only to be told that it was done by a third party ans MTN cannot assist me with cancelation. I was sent from pillar to post Aphiwe from upgrade dept dropped a call while still talking. The nos they provide for this third party company are not valid. Why us MTN outsourcing their sake to third parties that themselves cannot contact or even see what is happening on the sale?