Endless problems

I have been struggling with mtn OR Thambo branch now for almost 2 weeks regarding an upgrade i did first the took almost 3 days to do my upgrade and now a week later i am struggling to get my 30gb promo bundle loaded on my account and still haven't recieved any upgrade documentation i try calling the store and my call gets ignored i have even spoken to the manager Trevor and he is also ignoring my calls what do i do now this is very frustrating and tireing i regret signing another 24 months with MTN because this is the useless service i receive