Increased my monthly payment without notification

Cell C increased my contract amount without notification,my intend was to cancel this contract when it met its deadline,nobody notified me however,they just pushed up the monthly payments.This is now the second time this has happened.Furthermore,i never received a new handset or a notification of possible upgrade and or end of contract.Called the call centre,spoke to a very rude lady,also for the second time,to cancel said contract.Monthly instalment still went of my account,PLEASE HELP,I HAD THIS EXACT SAME PROBLEM BEFORE.Please call on below stated cell nr