Unable to assist with upgrade

I am due for an upgrade on January 2016. Unfortunately my phone fell and my whole screen cracked. Now I've contacted the call centre numerous times with no result. I've asked for an amount that I can pay to speed up the process of upgrading my phone. I was informed that the retention department will get back to me, 24 hours later, still nothing. After going into a store, I was informed that I need to buy myself out of my 24 month contract, ending up on R4500.00. With an installment of R500.00 per month, it would make sense that I am need to pay +- R1500.00 - as I don't want to pay for a new screen and upgrade 2 months later, however MTN wants to charge me R4500.00 and tell me that basically I need to restart my contract from scratch. I fully understand that this is a 24 month contract, and apparently they are already doing us a favor by letting customers upgrade on 20 months, but still not even willing to assist. Really disappointed MTN. Therefore I will replace my screen, and end my contract after the 7 months.