If the Independent Appeals Panel awards over €300k, the board of AIB has to approve it. They can either pay it in full or offer to limit it to €300k in full and final settlement. (It is similar for all the banks' redress schemes)
If they limit it, the borrower is fully within their rights to reject it and go to the Ombudsman or the Court.
But if it arises be very careful. I saw one case where AIB limited an award of €350k to €300k. AIB must have hoped that the guy would appeal it because the Appeals Panel decision was bizarre and their calculations were just plain wrong - they did not understand mortgages.
If the borrower had rejected it, I feel fairly sure that the Ombudsman would have awarded him nothing.
Brendan