Desktops forum: Problems with DELL

We own 2 dell computers and they have worked fine. However, one computer has windows xp and the other windows vista, my son thought that he could install the vista program on the other computer, he did not realize that you would need a product key to install it. I called dell customer service and was put in touch with a tech to help with my problem. I gave him the service number off the computer and he told me that we could install vista but that we would have to buy a $200.00 program to do it.When we got the program and tried to install it, it would not install. I called dell back and was told by a different tech that we needed to upgrade the computer before we could install the program. I wanted to send the program back but they will not take it because it has been opened. I understand that people do not normally take these kinds of things back. My problem with that is that I specifically asked the dell tech if the program would work on the computer and he told me that it would. Not only did I get charged over $200.00 for a computer program that will not work, they also charged me $39.00 to talk to this guy. Does anyone have any ideas on how to make them understand that it was their mistake and that they should take the program back?

Thanks