Cant escape from CellC

My contract expired earlier this year. I have 3 lines on the contract, 2 phone and 1 data. Being a pensioner, costs are very important. I wanted to change my contracts to something cheaper. The store consultant came up with a good solution, but CellC declined me. I therefore instructed CellC to cancel the data line as it had doubled in price. They would not cancel due to my account being in arrears as my bank had decided they would no longer honour the debit order 3 days before my pension was paid in and CellC would not change the date or cancel the debit order. That cost me approx R2000 in bank charges and extra charges fro. CellC. Eventually I caught up the account and asked again for the data Line to be cancelled. I was told I had to again give 30 days notice, which I duly did under sufferance. Ince again they have refused to cancel. I have just received my monthly statement and they have increased the fee. I called them again and was told that I have to again give 30 days notice. How on earth dies a person get CellC to act on instructions and support a loyal customer. I have been with CellC since December 2006. Tearing my hair out.