Urgent early upgrade

Good day.

I phoned MTN a couple of times and requested for an early upgrade on my contract. I have had this contract for longer than 7 years. Every time i phone they tell me i am in my first cycle, which i do not understand because of the total year i have this contract. I in desperate need of a new phone as mine is giving me a lot of problems. I run 2x businesses on this number and i am loosing customers because ether the phone keeps freezing or just does not want to receive calls. I have complaint about it several times bit no one seems to worry about it. For me it is a big problem. Please advise