That's weird, because when I had the RRoD on my first Xbox, I was told in no uncertain terms that the warranty would not be extended, and I accepted that. Other than that, the customer service I received from Microsoft was the best I've ever had, and indeed they even returned the replacement a week earlier than they said it would be (they'd said two weeks on the phone, and in emails, but it only took one week to arrive from Berlin). Fortunately for me with regards to my current machine, my second Xbox (the replacement) was stolen and so my current, third, one is from the insurance, and as such the warranty was replaced on that.
My point is that Microsoft aren't the evil greedy pigs everyone makes them out to be, and they told me exactly what their policy on warranties was and it was fine by me, so yes, in this case you were misinformed. It's not a problem with Microsoft's "shitty customer service", it's a problem with one guy who got things mixed up, and you're getting butt-hurt where there's no need to be. So either shut up and put up, or ditch it and get a PS3, either way don't complain on the internet about something that you're taking way out of proportion.