I have not come across this before and I don't see the point of it.
Before the Central Bank tracker review, Ulster Bank used to pursue case which they knew they would lose because they had lost similar cases, all the way until the exchange of correspondence was finished. Then out of the blue, they would write to the Ombudsman and ask them to put the case on hold while they tried to resolve the matter directly with the borrower. The borrower got their tracker back and compensation. The borrower then withdrew the complaint from the Ombudsman.
Ulster Bank's strategy was that many borrowers find the process exhausting and just give up. But for the ones who don't, they settle before an Ombudsman's decision as they did not want to appear on the Annual Report with lots of complaints upheld.
It's even more serious now. The Central Bank has told the banks that if the Ombudsman upholds a case on an issue that affects other people, then they must roll out that decision to all affected customers, whether they have complained or not.
My guess here, and it's only a guess, is that the bank either thinks that it's going to lose this or even if it thinks that it is going to win it, the risk of losing it is just too high. Let's say that there are 1,000 others facing this issue. Even if the chances of losing are only 10%, it would make sense for the bank to pay anything to avoid the complaint being upheld.
If I were the bank in this case, I would play the Ulster Bank trick and ask the Ombudsman to put the decision on hold while I try to settle directly with the customer.
So why are they asking for mediation? This just makes no sense at all to me. You complained to the bank. That got nowhere. You went through mediation, that got nowhere. You have probably used up a lot of time and energy at the investigation stage. I wonder are they trying to wear you out? Is it possible that if mediation fails, then the Ombudsman would go back to Square one, and you would wait another 4 years for a decision/
Here is what might go wrong. You agree to mediation in good faith. It fails. Then you or the bank make some comment to the person who is investigating, as distinct from mediating, your complaint. The mediation process is separate, but now your comment to the investigator has compromised the investigation, so they have to excuse themselves from the process and a new investigator is appointed.
So, you politely refuse to go back to mediation. You copy the person in the bank who wrote to the Ombudsman. You tell them that while you are refusing mediation, if the bank wishes to approach you directly to settle the case to your satisfaction, they may do so, but that should not hold back the issuing of a decision by the Ombudsman. If the bank makes you a suitable settlement offer, then you can withdraw your complaint. Any discussions with the bank would be without prejudice. In other words, if they make you an offer which you decline, you cannot tell the Ombudsman.