How do I escalate issue to Dell Management? No follow-up or accountability

I'm a busy primary care physician who relies on my computer to care for patients. Therefore, I decided to take the plunge and purchased a fully loaded Dell XPS 8930 SE desktop from Dell.com. After some months, the Solid State Drive fails and after spending considerable time with customer support, am told that I have to send it in for repairs. Desktop comes back with paperwork showing that they had to replace the solid state drive and the OS. I turn on the "serviced" desktop only to see issues with video card. I called Dell again and after remote-diagnostics am told that the Graphics Card has failed and needs replacement. I escalate the issue to Dell online customer support and am told that per policy they will send me a new graphics card and someone to fix it. I informed them that they have given me a faulty machine and that I don't want a desktop that keeps failing - please give me a replacement or refund but they refuse and say that they will "escalate" this issue further. I told them that this is like getting a brand new car being told that first the engine has failed and then later the A/C has failed too but, "too bad--we will only service issues until your warranty lasts". Being thrown back and forth between customer service reps with no resolution. Worst experience ever. I'm now stuck with a broken machine and being tossed around by Dell. Meanwhile, I have had to make arrangements for an alternative computer (using an Apple now temporarily) to access my patient's data and to continue to care for patients. No accountability or ownership of their product, and since tech support is outsourced, they could care less.