Poor service

I had a debit order from Cell C which I don't have have I did have a contract but they have all been paid up and I am not owing any money to you or any arrears I want my money back as our agreement is over. The contracts that I had before are cancelled and paid up this year I was even told that I would get a cancellation letter which has never been sent to me for this specific phone. My other contract also gave problems just trying to get a letter where Im sent from pillaer to post at the call centre. I was told to submit my statement which I have faxed and e-mailed Ive been to the Cell c store and no one is giving me answeres about my money !!! Please I want an answer today cause every time something goes wrong with Cell C and Im the one who must do the running around, the calling cause no one bothers to call me about it and still pay money thats unneccessary !!!!!