Next time you may wish to book directly on
www.aerlingus.com. (I've not flown TATL with Aer Lingus in 12 years, so I don't know if travel agents give competitive quotes these days for Aer Lingus TATL travel - but for European/short-haul travel, it's always considerably cheaper to book direct from EI than via a third party.)
That way you will be also able to play around with all the "Manage my Booking" options on their website - one of which is "Upgrade to Business Class".