INTERNET CONNECTION SIM CARD - Consumer Complaint for PEP STORES

I came to pep stores in setsing crescent mall and bought a cellphone for somebody. The Phone is a Mobicel Rio,costing R430 it is a dual sim. The sim which connects with the internet is sim1 and mtn only. My problem is that the person i bought the cellphone for says he uses vodacom for everything,i was asking the lady for me to top up on the 430 and get a new phone now im told i cant do such thing,meaning that money has gone to waste. They cannot do anything.