Studio 1555 Chronic Overheating

I first got my Studio 1555 laptop back in September of 2009.  I had saved money all summer to buy it before heading off to college.  I upgraded it with 1920x1080 resolution display, duo-core 2.80 GHz T9600 processor, 4GB of RAM, and numerous other hardware and aesthetic upgrades.  I planned on using it throughout my college career and maybe even a couple of years after.  However, four months after receiving it, the system started crashing.  It would abruptly turn off without any warning in the middle of whatever I was doing; usually playing a game or watching something full screen.  

After determining that heat was the culprit, I requested an in-home repair over spring break.  The technician failed to accurately address the issue, snapping the audio wires and replacing the motherboard, not the heatsink or fan.  I contacted Dell and informed them that I would like to send my system in for repairs at their servicing station.  They managed to get things fixed there, and I thought that was the end of it.  Then, over the summer, the same exact problem returned.  I skipped the in-home repairs and sent it straight to the servicing station.  It returned fixed, but now, just over five months later, it has begun overheating again.  

Does anyone know if there is a way I can exchange my laptop for an entirely different one?  I'm willing to sacrifice the aesthetic upgrades I made for a system I can rely on.  Or better yet, is there a way I can simply be refunded for my purchase?  I'd much rather get at least some of my investment back that I could put towards either building a desktop for myself, or getting a laptop from another company.  If not, I'm afraid I might have to try and go through eBay or something to get some of my money back.

TL;DR

After multiple trips to the service depot over the past year, Dell has failed to permanently repair the overheating issues which plague my laptop. Is it possible to either continue having it repaired after the warranty expires (for free), exchange it, or get a refund/partial refund?