Moved to higher interest rate

My wife recently took voluntary redundancy from knew of the financial services providers. As part of her benefits package while employed there she was entitled to a beneficial interest rate on part of the mortgage. So in 2008 we took a mortgage with them. 60% of the amount was @2.5% beneficial rate and the remainder was a tracker @ ecb +1% promotional rate. After a year the promo was up in the tracker part and they moved that part to ecb +2.25%.

Since she left last month we got a letter from the bank saying that as she has left the part of the mortgage that was 2.5% will be switched to 4.5% variable (increasing the mortgage by €170pm)

We have an appointment with the bank today and u want to argue the fact that had she nit been a staff member at all then we would now be on a mortgage with the entire amount on a tracker of ecb +2.25% and to ask can we return to this so that what was originally meant to be a benefit isn't now a crippling burden.
What do people think? Any advice on how to approach? Should we engage a solicitor if we get no joy?

Thanks.

Was she aware when she availed of the redundancy package that the entire mortgage would move once she left the bank?
I took voluntary redundancy from a financial institution about 10 years ago. As part of the severance agreement I was allowed to retain some benefits for 1 year (staff rate on house insurance being one) but it was made quite clear that other staff benefits would no longer be mine.

Usually that stuff is worked out between the union and the bank in the redundancy package, there must be some reference to what happens to existing loans in the redundancy offer she signed up to.

I also worked for a financial institution and saw several packages over the years including the one I eventually took, this issue was always part of the negotiations due to the fact that so many staff would have preferential rates on various loans and the details would be in the redundancy offer issued.