People/Organisations you can write to to voice your objections/concerns/ask for further investigation. I'll stick all the address details below.
The Central Bank
While the Central Bank don't accept individual complaints they do however take on board general observations. You would need to write to the Director of Consumer Protection.
Bernard Sheridan
Director of Consumer Protection
Central Bank
PO Box 559
Dame Street
Dublin 2
D02 P656
The Consumers' Association of Ireland
The Consumers' Association of Ireland are engaged in regular round table discussions with the Central Bank as stakeholders. If you have a concern about lapses in consumer protection it's well worth writing to them and asking them to lobby the Central Bank on your behalf. Their council and policy advisor is Dermot Jewell.
Consumers’ Association of Ireland
26 Upper Pembroke Street
Dublin 2.
Oireachtas Finance Committee
I've heard members of the committee mention on air that they would be in favour of convening of a specific tracker mortgage hearing/series of hearings. The more people that contact them, the more political will there will be to hold a specific hearing. They also mentioned that it would be beneficial for affected account holders to speak at the hearing and that they should not be limited to the Lenders and the Central Bank. There's huge merit in this because it puts a public face onto the issue, as opposed to stark facts and figures.
Committee on Finance, Public Expenditure and Reform, and Taoiseach
Leinster House
Kildare Street
Dublin
D02 XR20
You can also write to your own local TD (care of Leinster House).
Office Director Corporate Enforcement
If you can prove that the bank's actions were in breach of company law, then you can also make a complaint to the ODCE. Proof is essential here. There's a form you can fill out on the website, and make sure you make yourself familiar with the list of FAQ's before you send it in.
http://www.odce.ie/en-gb/faq/complaints.aspx
For what it's worth, typed letters are very effective. If you have the time, turning up at your local TD's clinic also works very well. Put a human face on the issue if you will.