No end to Cell C's debit order

I took out a data contract with Cell C 2 years ago for my tablet - 1G of data for R98,99 a month. Last year 21 Dec my contract expired. Obviously I had forgotten about it. The only warning I received from Cell C was a sms on my tablet - Cell C is unable to contact you. Please contact us. No warning of what was to come. On 31 Dec an amount of R232 was debited from my account by Cell C. Failing to notice this immediately another R279 went off as debit order 31 Jan 2015. <br> <br> I went in to the Tygervalley Cell C branch who explained that on expiration of your contract a fixed amount is charged per month - irrespective of how much data you used. (I was in an area with almost no reception over Jan and Dec ironically). <br> <br> I cancelled my contract on 2 Feb 2015 and was assured that I would be charged a pro rata rate for 1 and 2 Feb only. However on 28 Feb R279 was debited from my account again by Cell C. I reversed the debit order at the bank. Cell C told me I should phone after 7 March as the correct amount will then displayed on my account. I phoned on 12 March - My account still showed R279 outstanding. This morning R279 was debited from my account again by Cell C!!!!!