Thank you to those who have PM'd me & taken me seriously.
The Armed Forces Pension Society, of which I have been a member for a number of years, we're dismissive along the lines of, 'personal problem mate'. The SPVA's attitude is, 'yes, we got it wrong but tough'.
I seem to have litigation as the next option. I also realise that a solicitor or partnership will not take the case unless they consider there to be a greater than 50% chance of success - so it will be a good litmus test.
Thanks again.