Hidden cost not explained to customers

I have a problem with the above mentioned service provider which I app**** for data sim card of R299 and the consultant called me to finalised the deal but I was fortunate that I don't qualify for the above mentioned deal but I was offered a deal of 20GB + 20GB of R199 and I took it and the begin on the first debit and was R327 and before their debit date,I requested for a explanation at least breakdown the amount and they told me that the amount was pro rata bill and the next bill will normal R199,and I wanted them to explain why I didn't qualify for 120GB of R299 in the first place when I app**** for it while I could pay R327 bill and they never explained that and they went on to bill me R275 and I did write to them again demanding them to explain again but this time they never explain but ignored my email until the writing of this review.