For me it is a 10 hour drive to the nearest store and while I do like driving I'm not going to do a 10 hour drive there and back. Like you,I finally got to tier 3. Interesting response - product out of warranty. I also received an email from tier 2 support advising that if I take the touch key cover back to the store they will give me a price for a trade in. Novel. When I spoke with the store the reason I was phoning was to get their ABN (Australian Business Number) and registered office address in Australia. What was interesting is that the staff member point blank refused to give it. (I think that is illegal).
Anyway now I think I have received enough information and lack of assistance to report the problem to consumer affairs and/or our small claims court VCAT - Victorian Civil and Administrative Tribunal.
I had already tested my key board and computer in a retail store before I contacted Microsoft. And, yes, both pieces of equipment worked independently with the devices in the retail store.
cheers