Hi,
Have you told the dealer clearly that you don't believe that they sold you a car that was of merchantable quality?
If so, what's their response?
If not, you need to do so, clearly and given the history, while I'd initially look into meet them and discuss it, I would also present the statement, supported by a brief, factual, summary of the issues you've had, and asking for their written response within 14 days.
I also think you should insist that the dealer get the main distributor for Ireland involved in the conversation, if that has not already happened. While the dealer sold you the car, they'll very likely get some assistance from the distributor (with regards to resolving the issue), if it's a legitimate and well documented problem.
To be fair, 3-years seems like a long time to have let things go, so a full refund seems very unlikely.
Likewise, you selected the make and model, so the fact that you've since gone off it, lost faith in it, or seen another car that you now prefer, isn't the dealer, or manufacturers fault, so a very good trade in price against another car, seems the reasonable expectation here.