I wrote them a letter asking for specific information, thus enabling me to make an informed judgement over which option to take, which they weren't able to provide.
Wrote again, stating that as they were unable to provide said info, I was unable to make an informed decision at present, and elected to defer my decision until said info was available.
Gets phone call from annoyed whitehall chap saying can't do that. Says I, reminds me of the pension misselling saga, best you keep all my letters as they may form the basis of a legal challenge in the future.....goes very quiet on other end of phone.
I agreed to stay on 75 in the meantime. Preferred to keep my options open.