Housing benmefit suspended in error?

I have been asked to seek clarification on a strange case.
client has been in receipt of HB paid self, accrued £5k in arrears as failed to pay.

RSL managed to get monies paid direct to them, tenant has now advised LA that he has a dispute with RSL and they have suspended HB.

obviously tenancy is at risk but how do I pursue this..

as a WRO client will be entitled to all monies backdated but as there is previous for not paying would it be better to seek direct paymeny to RSL