Telkom Bill Shock

I got a new phone that was on special deal in July, it was a 1GB deal for R399 with a free phone, I got my statement the other day, they added R100 for the 1GB separately, I have R155 internet bundle data added, and some costs I don't know, all in all, I have to pay R760 as opposed to R399,can someone please call me and tell me what is going on here,I did not sign up for this,I would like like those additional costs to be removed from my bill please.