I purchased 9 refurbished Dell Optiplex 7010 Desktop Computers on January 28, 2020.  Two of the 9 did not work upon receipt.  The power light was flashing yellow and didn't turn on.  When I called, they emailed me two prepaid labels and sent two new computers, no questions asked, even before receiving the two computers I was returning.  Although I was disappointed with the computers not working, Tekrefurbs replaced them with no questions asked.  Between March and April 23, 2020, we had one more computer failure with a flashing yellow light, and one was replaced twice with computers that didn't work upon arrival.  I'm left with 2 non-functioning computers:  one with the yellow flashing light and one that says "rear fan failure" (which was received that way).  Tried to contact Tekrefurbs at least six times over a period of several weeks.  I finally contacted Amazon in July and was told because I dealt directly with Tekrefurbs instead of going through Amazon, Amazon had no record of anything that happened and there wasn't anything Amazon could do but attempt to contact the seller on my behalf.  I understood there was nothing Amazon could do because of no paper trail.  I appreciate the offer by Amazon to contact the seller.  The response I received from the seller was that the warranty had expired.Bottom line:  Deal with any vendor through Amazon.  NEVER buy from TekRefurbs.  Ask questions when buying refurbished computers from anyone regarding the warranty.  I never imagined that one of the computers that were originally purchased would be replaced within the 90-day warranty period twice (for a total of 3 computers) for that workstation.