Telkom billing contract nightmare

I took out a wifi contract wit Telkom the smart broad band wireless top for 80gigs for 499 every month the data doesn't even last until the next month u will find urself topping up spending extra ontop of tht u still get debited i called in wanting to cancel the contract and was told IL be liable to pay a cancelation fee and u will be billed for the usage of the data of the previous month how the **** does that work when u pay monthly for ur 80gigs u r given u was debited twice my monthly premium my credit score is getting messed up due to Telkoms billing systems I wouldn't recommend anyone to take out contracts with these ****ers ul be in debt