Cell c contract

I have never been so ****ed in my life. Cell c is the worst contact I have taken.They deducted their monthly fee twice this month on my account.When I called them for my refund,they are sending me from pillar to post saying they've called my phone is on voicemail.They keep on asking the same documents over and over but no progress.Ive been calling them since the 1st of March, no 1 is helping me then next thing they'll be saying I have arrears n***!!