XPS 8950, updates break computer

I am having the same problem as so so so many others.  The question is after so much time why is Dell selling computers to customers knowing that as soon as we do the update it breaks the computer?  First computer did the updates computer CPU speed stuck at .40 ghz, They sent me a new computer, now that the initial time is up they will not send me a new computer and I am on day 4 of no computer.  I have spoken to many technicians they do not even listen to me none of them.  Finally this morning I lost it and a tech kinda listened to me but no not really and I am still sitting with no computer and about to lose my job.  He just had me unplug my NVIDIA graphics card from the mother board and now my computer went from being slow to so slow its almost unusable. Yesterday tech took over my computer and did a system restore started at 9 in the morning and the system restored finally at 7 o'clock at night. 10 hours to do a system restore that is how slow this computer is.  All over dells sight there is issues with the latest bios upgrade to 1.15 conflicting with NVIDIA, but not one technician I speak to addresses this.  Finally this morning the tech kinda listened to me and attempted to restore the bios to default settings, but it will not revert.  And then he said he would call me back in 15 minutes and that was 40 minutes ago.