Absent tenant, no alternative contact details, right to rent question.

Letting Agents

I let a flat via an agent. They have rented it to a foreign national, his uncle pays six months rent in advance, he has now travelled abroad and access is needed to the flat for a reason that is not an emergency. The tenant is not answering his emails. I asked the agent if they had any alternative contract details for the tenant or his uncle and they say they have nothing. Shouldn't they have checked them under right to rent or money laundering rules? They have signed another contract for January to July 2021, but I don't know if they have paid yet, or whether the tenant has left. Any advice I would be grateful.