Cell C - *******

I have a contract with Cell C which is almost ending. I found out after checking my statement which i hardly opened before that they have been charging me money for a second line that i have no knowledge of.

I called the call centre to complain and after 5 days they come back to me saying that they will not refund me the money regardless of me knowing of even not using that data package they have been charging me for because i complained after 3 months of activation.

So now, this means that i am paying for something that i am not using and they can only cancel the contract but not pay me back the money i have paid.

What kind of thing is that. I need a refund of what i paid as i never used or received their sim card in the first place.