Cell C possible *****

Big was my surprise when I got a R 2900 bill from Cell C for a data contract that I stopped on 2018-01-02. I was at the Cell C shop in Somerset Mall and helped by Mark Nelson. I had to cancel this contract as the 2 years would have been over in February and I don't need it any more as I got fibre at home and have fibre at work. Mark then upgraded this contract to an open ended data contract from a fixed 2 gig per month contract before he cancelled it. As I had then only 1 gig left I used it without looking at the data left. That is where I got my surprise this month. My question is that why should I upgrade a data card for one month if I want it to be cancelled? The woman at Cell C customer care said that they got lot of ***** in the branched with this kind of thin as the salesmen get commission on sales. Then they let you sign all sorts of forms and slip the upgrade one in between. So it look very legal. I for sure did not agree to this. Now I have to get the shop to write a letter to Cell C customer care to state that I did not agree to this to get my money back. Yes - I did used the data, but as on a fixed data contract I expected for the data to run out and stop when it is depleted. I am thinking of getting SAPS involved for *****! Watch out for Cell C Somerset Mall.