Dell :: Getting A Refund After 10 Months

I've had my XPS 720 desktop since January. It can be a good computer, but I've had too many problems with it and Dell support has been terrible. I've had to literally contact them at least ten, probably a lot more times, for each problem that I've had. Since I'm typing this in an iPhone, I'll just list them.

Two weeks after I got the system it would freeze during the middle of its' boot up and I had to have a mediocre Dell technican fix it.

The system reboots (turns off out of nowhere and instantly powers back up).

The system got the "screech of death" and was repaired ten days afterward.

The technican that came scratched up the system a lot.

Tons of boot up errors before getting into Windows.

Does anybody have any tips on how to get a full refund from Dell? The system has gotten really annoying and there's really no excuse for them not to do something other than another repair and Dell isn't as good as it should be at fixing it. I'll probably focus on each point individually and put up a good arguement, though refunds are really hit and miss. I'll be talking to an agent's manager's manager tomorrow and I really just want a refund at this point.