XPS 420 hard drive crash

As nothing surprises me anymore with this piece of junk I bought from Dell 6 months ago they have now replaced my hard drive (motherboard was replaced twice, printer once, and the entire computer once) .  The tech came out took out the dead and replaced it with another one and said it would take awhile to program itself (or something like that) but that once it does what it needs to do my computer would be just like it was the day I received this piece of junk.  And he left after a whopping 5 minutes being here.  Well aside from loosing everything I had on the drive that crashed; I now have no desktop icons, my word, excel keeps asking for the product key code and when I enter it it says it is invalid, it will not acknowledge my printer, and this "new" hard drive is SUPER SLOW and I mean SUPER SLOW. 

Do I just give up and try to sell this system or what?  I'm just mom trying to get what I thought I paid for.  What should I do?  The thought of calling tech support to talk to someone who can't understand me and vice versa for the 100th time just makes me sick to think about -- UGH