"The legal battle against The West Brom lasted nearly three years before Property118 Action Group were triumphant"
In June, Property 118 won a Court of Appeal case against West Bromwich Building Society after it increased rates on its buy-to-let tracker.
Similarly to the West Brom case, the Financial Ombudsman Service ruled in favour of the Bank of Ireland and their right to increase the differential they charge.
However Property 118 says "the case law created by case against The West Brom is of little use to us" as the legal arguments are "very different".
It added that the cost to take Bank of Ireland to Court could "run into seven figures" which it can't afford, but has "a legal strategy to enable affected borrowers to claim compensation".
Property 118's initial action will not be against the Bank of Ireland, but the law firms involved in advising upon and completing the mortgages.
Property 118 founder Mark Alexander said: "The legal battle against The West Brom lasted nearly three years before Property118 Action Group were triumphant – the Court of Appeal eventually overruled the Financial Ombudsman Service and found against The West Brom, who were then compelled to refund a reported £27,500,000. We believe compensation claims relating to the Bank of Ireland tracker rate differential increase could more than double this figure."
The Property 118 Action Group are also crowdfunding to take action against Skipton Building Society.
