If the bank doesn't see Ryanair even trying to charge your card then that's quite weird indeed .. Problem must lie with whatever validation Ryanair is running on your card before they even try to process the payment ( They do things like spotting obviously invalid card numbers due to typos etc. ) .. if they were genuinely getting decline messages from your bank then the bank would surely see this and tell you ...
Normally when this type of thing has happened to me booking flights on strange airline websites it's a simple question of calling the credit card company and getting them to confirm they blocked the transaction and instructing them not to block it again ( Some credit card companies have blanked blocks on some airline sites due to elevated fraud risk, but Ryanair wouldn't normally be on that list !) .. but this doesn't sound like what's happening here.
You can try to talk to them on their new "live chat" service on their website .. but I'm not sure that' would be that useful .. Aer Lingus might be a better option than wasting > 30 Euro of your time !