UC Review and possible overpayment problem

Hi
A vulnerable friend, who has learning difficulties, has been on UC (LCWRA) since 2021.
He has a UC Review telephone appointment next week and his friend uploaded 4 bank statements on his UC Journal.

His friend has noticed one of these bank statements shows a “rent refund” credit of £347.58 in July 2025 …….. for a flat he’d actually moved out of 2 years earlier!

The claimant doesn’t check his bank statements and so was unaware (until now) that he’d received this “rent refund”.
I contacted his (former) letting agent manager this week who, after investigating, confirmed they have no idea why they sent him this payment, out of the blue, in 2025.
She confirmed my friend’s rent was not overpaid during his 2021-2023 tenancy and that, in fact, their accounts show a “rent refund” has been made in 2025 to all the tenants (who all moved out of their flats in 2023 due to non-fault eviction). It isn’t their deposits (which were promptly returned in 2023).

They are continuing to investigate but don’t know whether they’ll be able to get to the bottom of it before my friend’s UC Review appointment next week.
The letting agents are willing to write a letter - if necessary (to send to UC)- confirming they’re investigating this payment.

As UC Housing Element covered his monthly rent in full (paid into claimant’s bank account), do you think it’s likely DWP will regard this “rent refund” as an overpayment?
Perhaps it may turn out to be a “compensation” payment instead. It’s just not known at the minute. However, the letting agent have confirmed they don’t want it to be paid back to them as it wasn’t e.g. a computer glitch error.

My friend has no savings so there won’t be any issues about savings during his Review.

He has severe anxiety and is so worried about getting into trouble and getting a fine from UC/DWP and the Review dragging on and on.
His friend (who will be doing the UC telephone Review with him) thinks it’s best to wait to see if the UC Agent ask about this transaction and then explain that the Letting Agent are investigating.
The claimant wants to do that too- it’s causing him so much anxiety.

Do you think that’s ok? (to wait until if/when they ask during next week’s Review)?

Or does DWP need to be informed about it in advance of next week’s UC review?

I’d be very grateful if anyone can advise. Thanks so much for any thoughts you might have.