Falls selling

I took a contract phone 5 days ago, I told the sales agent clearly that I don't want open line but prepaid because I'm buying this phone for my daughter and she said I can change it back to pre paid immediately after getting the phone and went as far as giving me steps to follow. But to my surprise today when I call in I can't change it before 3 months.... I'm extremely ****ed and unfortunately should my daughter exceed the data allocated and start using over that I will not pay for it because I clearly stated you can listen to the recording that I want a prepaid line. The agent name is Bongeka, cinthia kheswa if she gave me the correct name