Have you spoken with the owner of the establishment? That would be my next call. Chances are real good that the owner would rather have a satisfied customer and positive feedback. Chances are also good that, if this is an employee, this ain't the first time he has been disingenuous. It always helps to take it up the line.
If no satisfaction is gained there, then there are always regulatory agencies who, though they may take no action, should be willing to at least hear your complaint. If they are doing their job, then a series of complaints may result in an investigation into their sales practices. And if you do talk to an agency, make sure the shop knows about it. Not in a threatening manner, just a "Hey, so you know, I filed a complaint with XXX due to what I consider poor treatment and response by your place of business".
