Are Lingus - Checked in online but forgot to add book in bag

Got to the airport this morning to go on holidays. Lady at the Aer Lingus desk said we never booked in our bags.

It was my bad. Holiday booked months ago, did online check in during the week, but in my haste I never booked in our bags. Cost us €45 per bag at airport. €90 in total. Bad start to holiday.

Trying to avoid the same on the return flight but I've already checked in online for the return flight. When I try to Manage my Booking on the Are Lingus website now I only get the message: It is not possible to retrieve this booking as all passengers have already checked in.

Anyone know a way that I can check in our bags before the return flight???

Thanks!