Having been around a long time, here’s how the use of Concierge upgrades have changed.
1. In the past I could ring Aer Club and I could be told there and then if upgrades were available and I could book an economy flight (cheap saver ticket equivalent) with 100% knowledge that all was well.
2. This changed when Aer Club weren’t able to tell immediately if an upgrade was available but Aer Club members could book the flights and if upgrades were not granted, then the member could cancel the flights (even on a saver ticket) and receive a full refund and try and book some other dates.
3. This changed again to the current situation whereby if you buy a saver fare and the upgrade voucher is not granted, no refund is given and the passenger must accept Economy or not travel.
If you decide not to travel in the case where one leg has been granted, or look to change your dates, then any upgrades granted are lost.