That sucks OP. They should have offered you something else as compensation, can't believe they STILL messed up the keyboard. WTH is going on eh?
All the Apple store around me in the GTA have been pretty much perfect (apart from BO and too-weak AC in the summer), Square One, Sherway Gardens, Yorkdale, Eaton Centre. They've replaced whatever I've needed ASAP/on the spot.
Over the phone, they've even sent me a free battery out of warranty for a white Macbook back in the day.
Another time, I bought a used iPad that came with a nasty smart cover with those marks on the metal (the magnets attract minute filings of metal over time from the constant attaching/detaching) and saw that people are getting replacements, so I went in, and wanted to pay extra for the leather one, but they wouldn't let me and replaced it with the plastic gray one. I came home, called Apple and asked if I could pay extra over the phone, and the rep apologized to me profusely for "my experience" and sent me a free red leather cover.
Members in other places bringing up consumer protection law - ours in Canada is super strong as well (part of why Canada is consistently at the top of a lot of statistical rankings, and far better than the UK I might add), but that has jack to with OPs experience. As a customer, you come across poorly-managed establishments, and that's all that happened here.
Those who have said there's another side etc... BS. OP is a paying customer and is entitled to the service he paid for, plain and simple.