Sales consultants didn't explain terms of the contract

I am utterly disgusted with the service I received from Cell C Empangeni. I took out a contract for a phone in July because there was a special going on. However what the sales people didn't explain to me is that there is going to a pro rata for the duration of the month and they put a 500MB data bundle on my account FOR NO APPARENT reason after i EXPLICITLY told them that I have wifi and want a fixed contract since I don't data.

This is the most sloppiest service I have received in a long time.