So an A330 is still in maintenance, therefore they're nicking an 757 from Shannon for Dublin to Boston?
Not only do they have to refund or transfer the passengers booked from Shannon, but also offload surplus at Dublin too and handle them?
One wonders how that was simpler and cheaper than hiring an HiFly A340 or whatever for a few days.
'Use it or lose it' they say of the Shannon services, now with the disclaimer 'unless Dublin needs it whereby you lose it anyway'.