MTN BAD SERVICE

I have a cellphone contract with Mtn from 2013 december and i took insurance with the 9990 Black Berry and i started experincing probles last year october when my phone felt in the water and i took the phone for repairs in october 2014 and since then i have been calling the insurance department for more than six months and still no help and i was supposed to upgrade december 2014 and i didnt because of this bad customer service i receive from Mtn and they are still debiting my acc with R263 and i only have a sim card which i receive R100 airtime and it is not fair on me because when i call the department they always drop my phone or put me on hold for the ever and i called them today and spoke to Busi Kunene who placed me on hold for 30 minutes and dropped my call and i spoke to Mark Maleking the supervisor and he is like his team and he doesnt care at all and i am tired with mtn just want to cancel my contract