incorrect billing that has not beed addressed

i have been trying to complain to MTN for incorrect billing for months. since April I have been complaining but no one seems to care or even take down my complaints. every time I call they tell me there is no previous complaint in the system. I was overbilled in April June and July and I have called 808 10 times and every time they say I will have a response in the next 48 hours but no one has ever called me. I am starting to think mtn is doing this deliberately to all customers as a way of *****ing money from us. and I cant wait for my contract to expire so that I can move to another network.