Advice needed on Domiciliary Care Allowance problem re old closed bank account

Hi I am waiting 3 years for carers allowance, as i can't give them details of a bank account we heald years ago, they are closed i got letters from bank stating they are closed also

What details are they looking for?
Why can't you get these from the bank or your own records?
Have you considered making a complaint or appeal (maybe not applicable if your application hasn't actually been rejected yet?) to social welfare over this?

Why do they want details of a bank acc you held years ago?

Whats the background or context here.

It should be simply a case of giving your current bank acc etc.