Garry: What are our options then? They aren't dependent on me, so they don't qualify for the 'grandparent' settlement visa either.....

I don't know what would be best. I don't want them to lose their money applying for the RPOIM visa if they're not going to get it due to age.
This is the paragraph I was referring to earlier:
19.9 - Discretion in exceptional cases
In very exceptional cases you may judge that while the applicant does not fully qualify, the application meets the spirit of the Rules (e.g. where an applicant has not reached the age of 60 but clearly intends to retire, or has already done so). You should refer such cases for a decision to the Integrated Casework Directorate (ICD), Home Office.