Overcharge

My cheque account was recently debited with an amount of R2197.78 for internet services. I entered into a internet contract in February 2013 (contract nr ***75668. I was told by the person who drew up the contract that it was for 24 months as most internet contracts are for this period. The monthly contract charge was R98.99. On the 1st February 2014 my bank account was debited with an amount of R2197.78 for out of contract internet data usage. This is almost 22 times the monthly rate I was paying for the service. I was informed that the contract was not for 24 months but only 18 months. This being the case, why was my internet access kept intact despite my contract having expired. When I speak to other Suppliers they tell me that when a contract has expired, they stop all further internet access, and inform the client to take out a new contract. It appears that Cell C do not follow this route and continue to provide the service, but at \over the top rates"I am a 73 year old pensioner and this charge has placed me in a financial predicament. I am sure that Cell C have willingly kept my account active"