Dell has a bait and switch on their on-site extended warranty Round Rock Texas

I have a multifunction computer here that I own and purchased directly from Dell.  I use it to remote control my clients computers.. specifically with higher resolutions. I intentionally purchased an "on-site extended accidental warrantee" from Dell as this computer has client data on it and I do not want that leaving my house/office.  Also I could not afford the down time.  Also I have had bad experiences with their mail-in depot and prefer to keep my computer within my eye-line.This computer is very difficult to take apart and work on.  Also, doing so would void the warrantee. So near the beginning of the warrantee the screen cracked.  (very fragile computer). Dell took about 3 times of sending people out, and hours on the phone with me yelling at them till they finally sent the correct parts with a tech to repair the computer. A few months ago the screen got a little nick in the corner and it was affecting the touch ability.  So I called in another service call. They sent a guy out.. I told him to make sure he had the right parts FIRST... He took an hour to take the computer apart realized the part was wrong.. and the screen sent was not touch.  put it back together.  Badly cracked the screen in the process... Sent the guy out again.. same thing happened.. This time a ribbon was hanging in the screen. Sent another guy out.. same thing happened. Sent another guy out.. He did something to my computer so it would not turn on.  He spent 30 minutes fiddling with it and got it to turn on.  But warned me it now needed a new motherboard and not to turn it off.  (eventually the power went out and the computer has never worked again)

A couple more times they dispatched people but they did not have a motherboard or a touch screen either.
This went on about 6 times in total I think.
I have multiple calls recorded to Dell where they assure me they will fix my computer on-site and not bait and switch me.
Yet... they INSIST they cannot fix my computer on-site and demand I send it into the depot because my on-site warrantee does not support fixing the computer on-site.   Despite having precedent of them doing so.  When I ask them about that they just say, "Well that was an exception". I have phone recordings and eMails for all of this. 
I imagine a well targeted query of their records would show thousands of people they were doing this too.
This seems like the perfect making of a class action suit that I would love to be at the front of.  (: