DWP ESA error lump sum for under payment. Can UC claim this back?

Hi, I have just subscribed as been told it's the best for benefit queries. Hope somebody can advise me on the following.

I have been on disability benefits since 2006(my Husband is my full time carer & claims CA) & when we moved from Wales to England in 2018 we had to migrate from the legacy benefits(DLA,IS etc) to PIP,ESA & UC.

In December 2025 I contacted ESA as I hadn't realised that I had not been receiving the £10 Christmas bonus. They said they would put me back onto it, but I probably would not be intitled to any backdated payments of the bonus.

7th January I received a phone call from ESA, telling me that they had looked into my claim & discovered I had been put on "income" ESA instead of "contribution based". So I had been under paid for 7 years. Meaning I was due a lump sum of over £26,000 which included the £70 back dated Christmas bonus. I was advised to go on my UC account & make a journal entry explaining what had happened & enter the amount under savings/investments, tick the box for benefit underpayment, but as it was an error by the DWP this money would be disregarded for a min of 12 months & in some case until my claim stopped. This is also stated in the Letter from ESA.

19th January, I received a reply to my Journal entry of the 7th, saying the following
" ESA is classed as an "other benefit" for Universal Credit purposes and is deducted from your monthly payment.
You can see this in your monthly statement, under deductions for yourself.
I will need to contact ESA to see what the arrears they paid are for.
If it is because the rate they paid you was incorrect we will have to recalculate the Universal Credit you have been paid from December 2018."

Does this mean they will want to claim that money back(as I get my ESA deducted from our UC)? If so how much per month & how will it effect our UC payments as its a joint claim,plus we get support payment for 1 child & Housing benefit.

Thanks