Incorrect billing

I have cancelled my services with supersonic and they attempted to debit my account of almost R2500.leading up to this event when I spoke to a cancellation department representative.opon agreement to cancel the month-month to service the rep said I have to wait a month and asking the rep on numerous occasions if I had any fees they mentioned I don't have to pay any termination fees, I asked as well how to return the modem they have said a courier will pick it up...3months later service is cancelled I was waiting for a courier van to take the modem and next thing you know they want almost R2500 from me.I going phone and you better have the answers because you have *********** reps who don't know what they are doing when placing me on hold constantly and don't have the answers....i am disgusted at the manner in which your company conducts it business practice I not going to pay zero rands to you...