Advanced Exchange request denied, no reasonable answer as to why

It's been a month since Dell offered me a replacement laptop under warranty, due to failure to fix my current laptop on site 3 different times. I keep being led around in circles, and am beyond frustrated. The current laptop is getting me through my job barely - wifi doesn't work, so it needs to be plugged in. It still crashes intermittently, but I have been getting by, waiting for the replacement. Dell keeps sending me the one-time use link to enter my credit card info for the advanced exchange - upon entering my CC info, i am brought to a page saying it was successful, but i immediately receive an email saying "Your Advanced Exchange request was not approved". Dell is blaming my credit card, but i've tried multiple cards and confirmed with the credit card companies that my card is NOT the issue. Furthermore, they've assured me Dell never even ATTEMPTED to place a hold on the card. Nobody is giving me a straight answer, other than telling me i can send this broken laptop in to Dell, and 10 days later, they'll send me out the replacement laptop. I CANNOT go 10 days without a laptop - I WILL LOSE MY JOB. I've explained this to them MANY times. Please look in to this and let me know what can be done.