DLA, residential rehab, client contribution and official error?

This is mentioned in passing in CPAG P.919 but I can’t find anything further.

Client went into residential rehab funded by LA for about 6 months. Financial assessment took into account his DLA (HRC/LRM) income and he paid about £70 p/w towards the cost. He did not declare to DLA that he had gone into the rehab so payment of both components continued.

If he does now declares it/is found out, what happens about the payments he made towards the cost himself? Are we looking at a Tax Credits overpayment and HB situation where the overpaid income is counted as income anyway, or is there any means of recovering his contribution to partially offset the DLA overpayment?

Also, is there any chance of arguing that official error contributed towards the overpayment as the LA continued to use his DLA Care income in the financial assessment throughout the 6 months even though it would have been aware that it should have stopped after 28 days?

As client in rehab they are clearly vulnerable therefore it would be reasonable to expect support should have been provided to ensure DWP were updated with regard to their change of circumstances. The LA should have informed DWP as well, the Financial Assessment needs to be reviewed as soon as possible and DWP need to amend the DLA award, it is however highly likely that it will take an extended period of time before the DWP actually calculate and notify the actual overpayment of DLA.

In terms of the HB situation the LA benefits team will need to liaise with the social care financial assessment team to resolve the situation as it appears to be an official error. Am assuming client is not a S117?