Poor quality, XPS 8930. How to resolve my issue?

I bought a XPS 8930 last month, this is a begining of a nightmare. The first one was damaged and 2 USB ports no work. I trust Rep of Dell to replacement not return because he said I can return if the second is still quality bad. The second one arrived on May 25,2018. Always blue screen errors and restart. The Dell Technician remote control my computer to fix it. Only 1 hour, the blue screen message come back. I call Dell Rep to return today, Dell Rep transfer my phone to 9 department, I repeat and repeat my order number, purchase ID and service tag to every Rep for 2 hour, until the last Rep, she is a lady, she just ask my name and hang up. I do not understand why Dell Rep kick customer like a ball.I was kick to here and there, nobody want resolve my issue. Is this Dell's service? Horrible. I call service phone number 1-800-624-9897 again. A lady claims she is manage, the so-called manage's attitude was more scurviness,she said I can not return because past the date of invoice, Dell issued the invoice, I never saw the invoice and nobody tell me why put  invoice of the first computer on the second one.Is this a trap? or Every Rep cheat customer, is this Dell service culture? I did everything great as a customer and made best effort to cooprate with Dell. Should I get the return from Dell? How to resolve my issue to return the poor quality XPS 8930?