I just read this entire thread. Bought a Macbook Pro the other day and am worried that if I get problems I'll have all this crap to deal with. I'm seriously hoping this is a (VERY) isolated case.
Regardless, I'm glad you finally got your way! If it were me, after the third repair I would've been demanding a replacement unit. You have, after all, paid for the extended insurance.
Don't feel bad for sticking up for yourself. There may be human beings on the other end of the phone/desk, but the bottom line is that you paid for a product, it doesn't work and you want things fixed properly.