I have to disagree with the above if that is ok.
I will use ourselves as an example. I think we went mortgage approved in October 2008 but didn't draw down until early Jan 2009, so 4 months past trackers being withdrawn to new entrants, we got that letter like everyone else at the time. We would have worked away in good faith that we were not entitled to a tracker and such is life.
We did however have clause 3.2 in our mortgage contracts. This clause being in the contract for new mortgages post the withdrawal of trackers is a mistake by AIB, plain and simple. I don't believe there was a grand plan to rip us off, it was a mistake, all be it a mistake in a legally binding contract.
It would be really interesting to see a breakdown of the legion between pre October 2008 and post October 2008 when mortgages were drawn down. If it was post October 2008, then you are unequivocally blessed to have clause 3.2. I think. Heck even if you a little before October 2008, AIB never intended to charge you whatever your first fixed rate was and then cut that rate in half. For the rest of your mortgage or until ECB rates recovered, which could be another 5/10 years. If people were truthful, they never entered their mortgages expecting that either.
Years later, way cleverer people than me saw the value in 3.2 and won a case with the FSPO and AIB lost and AIB lost badly, and this isn't over either.
Granted, of course there was a contractual entitlement to a tracker in the mortgage contracts but the reality is a lot more nuanced. In my opinion anyway. People can feel aggrieved or people can feel grateful, up to the person I suppose.