Dell will not replace a lemon of a computer

I purchased an Alienware, Area 51 Laptop in September. It is the best of the best that they offer. By November, my computer was freezing and causing significant issues on very important work calls with clients. Turns out that the motherboard needed to be replaced. At Dell's direction, I took it to an authorized repair shop and go it replaced. Brought the computer home and within an hour the motherboard went out again. Dell then sent an in-home tech to replace the motherboard and hard drive. An hour after they left, the power button wasn't working. They sent a new tech this morning to replace the power button, but they guy said there are broken pieces on the 3rd motherboard (obviously poorly refurbished). 

I'm now needing multiple items replaced, likely the motherboard, power button...who knows what else. 

Dell will not replace this lemon. I'm about to be on my 4th motherboard for a computer I've owned for 4 months and only been able to be used for 2 months. My new computer is now scratched up, lights don't work, etc...not to mention the many hours and billable time I've lost from my small business dealing with this thing. 

At this point, it makes zero financial sense for Dell to keep fixing this computer. It's beyond me why they won't do the right thing and send me a new computer. 

I cannot express how much I regret buying this computer.