Miss leading adversting and with holding informati

On the 9th Sep 2015. I upgraded my phone and I took data contract for R99 PER month 2G, I was not informed at the store that once you have used up the 2G it will charge for up to R2000, I my understanding was that once the data is finished it stops working. I was never informed of this, my phone has limited of R500, why would I leave my date to be R2000. Cell C know I don't earn more the R10 000 where would I get R3350 for phones. I call them asking them to stop everything, now I see they have charged me R2500. I HATE CellC. I bought what was adverts on the leaflet which was R99. NOT R2000. PPL don't believe what Cell C says