I gave notification to cancel!!!

Subsequent to calling in to notify yourselves that I will not be carrying on with the contract you guys have gona and billed me an amount that is even double what I used to pay. I am not happy about this and need this resolved asap. I will not appreciate it if you guys go and debit that amount on my statement. I specifically called and gave notification that this contract should be cancelled. Please do the needful and correct the statement that should only reflect R98 which should also be the last amount debited by yourselves from my account.