What would be the best method to make a complaint against a store rep and her managment that provided false information to sell me phone?

[Treye]

I was told by a store rep that a phone that I was purchasing had visual voice mail.  I purchased 2 phones of this same type only to find out 3 days later that even with the icon they still do not have visual voice mail.  I traded in 2 great phones for these 2 phones and when I went to return them, I found out then that they way she rung them up I would have to return both phones in order to get half of my money back due to the restocking fees and I would lose all of the airtime that I had purchased as well all due to the misrepresentation.