Poor service from mtn

For the past two months mtn has not kept up with the contract agreement as per data allocation. My wife has been on the phone everyday and every time a new ticket is logged. We have even been told that it has been loaded but there is no trace of it. Why do we have to pay for a product we are not receiving. Just not pay your account on time and your line gets suspended. Some one at mtn must be able to rectify this. We want to cancel this contract but now we have to pay a cancellation fee why because of someone else's incompetence. Really now