Cell C's poor service

For many years I had a cellphone contract with cell C. To cancel the contract I gave three months notice after which I was informed by their staff to give one month's notice. I gave one month notice on the end of April for the end of May. It was excepted by them and I was informed that the last month's installment would be deducted end of May, I was never informed that I had to come and pay at the branch of Cell C. After 17 days in which period they did not deduct money or phone me to inform me to come to the branch. I was handed over to the lawyers for an amount of R435 -00 . The lawyers then informed me I had to pay an amount of R980. Because of their negligence I had to pay more than double. Normally I would have been informed of the last installment as required by Cell C. This did not happen and I am of the opinion that this was negligence on a big scale. Cell C should take responsibility for the poor performance of their staff. This is another poor performance example of Cell C service to their customers. Beware anybody who wants to use Cell C as a service provider.