I have read over everything and I think I see the problem. I'm guessing you had a non-refundable ticket. You then cancelled the ticket. Since you cancelled the ticket, you are not entitled to anything.
But then, Aer Lingus cancelled the flight so you believe you should get your money back. One problem....you already cancelled the flight so when the airline cancelled the flight, you no longer had a valid ticket. No valid ticket, no refund.
You are not alone. Back then, we had numerous threads about people who cancelled their flights instead of waiting for the airline to cancel it.
If you had booked directly with the airline, they would not have owed you anything but the might have taken pity on you.
Airlines, like hotels and rent a car companies, like loyal customers. Those customers book direct and belong to their frequent use program. When I book anything, I book directly with the airline/hotel/rent a car company and make sure I enter my frequent use membership number. Even if I won't ever use it again, I"m one step ahead of the customer that doesn't have it.