Mtn
No signal at all

I have a blackberry bold 9900 - that half of the time is on edge and is awfully slow, i don't know why i have a decent phone if there is no cellphone reception???
everyone else in my household is with cell c without any complaints??
what to do?
can anyone tell me when MTN will pick up there service - cause i feel like cancelling my contract halfway through even if i have to pay all the penalties