Back payment after DWP error dating back to 2019.

The claimant receives PIP and Income related ESA.
The claimant received a telephone call from The ESA section of the DWP to say that as a result of a pending PIP review the ESA section discovered that they had been failing to pay Severe Disability Premium on their claim.
This error on their part dated back to 2019 and resulted in several thousand pounds being deposited in the claimants bank account.
The ESA caller assured the claimant that this large amount would not be counted as capital of the claimant for as long as the claim remains active. The ESA caller also assured the claimant that it would not be counted as capital when they migrated to Universal credit.
Are those assurances correct?
The claimant wishes to use the sum to repay their parents monies owed over a large number of years.
Is this acceptable , or would it cause any potential difficulties to the claimants claim in the future?
Any answers would be gratefully received.

Dodo.

Keep receipts when you pay off debts

I thought it was disregarded for 12 months if it's an underpayment, the magic word to search for here is "disregard" the DWP term for ignoring savings

thanks, I think if it was me I'd be checking despite what the person on the phone said.

I noticed recently that money paid into a recognised pension scheme is disregarded indefinitely, the question about savings over £6000 seems to come up on here regularly, if people aren't able to run a business and keep some extra savings for business use then it might be a good option, I was put off pensions by not being able to access money until the age of 57, and the fact that the age has been raised a few times, seems like that could happen continuously (but probably won't)

I should look this up but is "official error" a separate category? I've got a PIP MR to do at the moment, the deadline is looming, the assessment report from 2019 was a tissue of lies, that one was turned down and I missed the MR deadline so re-applied, but the current report keeps referencing this previous assessment "no problems found last time", I submitted a GDPR rectification request to get the old report corrected, this was acknowledged by the DWP GDPR team and sent to the PIP team but nothing was ever done, seems like an official error to me.