Experiencing the exact same issue. Mtn Supersonic support agent named Princess told me that they don't care about resolving the issue, after a fault had been logged four days ago.
They will probably give you the same response I received which is to state that your house is far away from the closest tower.Your best option would just to cancel and try and obtain a better provider instead of paying for their crappy product.
The messed up part is compared to other providers,Cell C signal always provides full bars on the huawei web interface.Yet the connection speed(if you can connect) is abysmal.