CELL C **** TO ME

I am so angry - i have been having the same fight since last year! Cell C promised me additional 900 minutes when I renewed my contract plus 4 GB of data which I have in writing. They tried to deny it and then tracked down the person who promised me I would get it. I got it in January but guess what - NOT LOADED FOR FEBRUARY AND THEY ARE NOT RESPONDING. NO-ONE else knows anything about it - I want to cancel this stupid contract