Over charging your customers

I took a contract by mtn for data r469 2years ago n now we i wanted to cancel my contract due me being under debt counsel and nt being able to ugrade. The they informed me now i owe them r3468.33 and i dont know where it came from al i was told was if i want to cancel my contract i need to do da last month of my contract whic i wanted to do today but now i need to pay the more koney which i dont have and i wont pay it because its infair service that they never even informed me about the last month that wont have any discounts in its not professional i will never tell anyone to take a contract out by mtn ever or buy anything by them. Im soooo disappointed i cant get upgrade and nowi also owe r3468.33 please people stay away from mtn. This is not my only problem with them it s the second complant already.