Okay, so you are getting nowhere with Dell.
You can't speak to the right person, they aren't honoring your warranty, won't service your machine, have denied your fourth refund request...any of this familiar?
Here's how you put the pressure (and the workload) on:
Better Business Bureau - File a complaint with the BBB to get some advocacy for your issue and get the problem with Dell on public record. Make sure you have all your correspondence with Dell at hand and a note of personal time spent trying to resolve the issue, the more details the better.
Federal Trade Commission - The FTC is the nation's consumer protection agency, it collects complaints about companies, business practices and identity theft. File a complaint here too.
Attorney General's Office - Find your state's AGO in this index, visit the web page and submit a public and legal complaint (not a lawsuit) against DELL.
Be firm and give the impression that if the situation is not resolved by these three (free and easy) means, that you intend to consult legal aid even if it never gets to that stage.
