Couple allowance of ESA and recourse to public funds

Would appreciate any insights…

- Client’s husband originally had no recourse to public funds. So he was included in client’s ESA claim, but she got single allowance only
- 2020 husband gets recourse. Client doesn’t inform ESA.
- July 2023 husband applies for CA
- early August 2023 (after immigration status checks) husband awarded CA from April 2023 (the standard 3 month back-dating). FULL amount paid (i.e. no adjustment against ESA to avoid overpayment). Client doesn’t inform ESA
- late August 2023 we send letter to ESA informing of husband’s recourse (by Signed For, but receipt mislaid). ESA says letter not received.
- October 2023 we resend letter informing ESA of husband’s recourse. Its arrival is confirmed.
- November 2023 ESA becomes aware of the CA award and applies Carers Premium (plus overpayment!) right back to April 2023
- January 2024 ESA decides to award couple allowance from October 2023 (date of second copy of letter)

So… The CA department of DWP had made a decision that husband had recourse from April 2023. The ESA department of DWP has not (yet) taken this date on board. The ESA couple allowance has not been paid from April - October 2023. I believe it should be.

Of course it would have been much better if my client had informed ESA of each development within a month. I plan to try and argue the 13-month rule.

But my gut feeling is that, since a decision of Recourse to Public Funds was made by DWP (CA) from April 2023, DWP (ESA) should add couples allowance from then, anyway. Am I right? Any suggestion for something to quote on this?

Any argument we can use about our original letter being lost in the post (or the ESA office)? Any other ideas?

Thanks in advance for your help.