Malfunctioning new system & poor customer service

Hello Everyone.  Over the years, I have purchased several computers and parts from Dell and have always been happy with their customer service. This time I have had the WORST experience with any company that I have ever done business with. Here's what happened (short version):

I bought a new laptop in June of this year (2015.) I experienced error messages warning that the AC Adapter was not recognized. The system slowed down to an un-useable state.  I called tech several times and DELL decided that the problem was 1) the adapter 2) the Windows10 known glitch, or 3) the faulty Motherboard. (This happened over a period of 4 - 5 months.)

The problem is still not fixed. I have to download a new BIOS file daily in order to have use of my computer. It dies during my work as well as during leisure. Every time I call DELL to speak to someone, I have to spend at least 1/2 hour on the phone for the new low-level CSR to catch up. 

This morning, my usual call to DELL for help, resulted in "Your warranty is expiring." 

I have not had a properly working system since I bought it. What would YOU do?