In most cases coverage problems can be addressed. It depends on the area, geographic contraints and also the existing infrastrcuture. We do find that in some areas the only possible way to address a coverage problem is to construct a new tower, and this has to be planned (due to costs running into millions of rands). However, in most cases it is possible to address using booster antennas. If MTN determine that this may be a benefit to other users in the area, they erect the antenna at their own cost, however in other instances they may negotiate a fee to do so, usually this is to cover some basic costs.
You can also check whether the coverage problem relates to using multiple networks, like moving between 2G and 3G. This can be resolved by forcing your device onto the 3G network only, which is a good option if you use your Mobile Data in a single location (not really advisable if you are moving around, unless you only want 3G data).