Difficulty with a tenant

Rent Arrears

Hi all, I have an AST tenancy with 2 tenants, a father and son. They moved in in March 2020 and it has been an absolute nightmare with late payment of rent (currently 3.5k arrears).

Recently the son has gotten in touch with me to say that he is happy to settle some of the rent but wants out. He is estranged now from his father stating he was impossible to live with. With it being joint and several liability he is also trying to persuade his father to leave but not having as much success as his father doesn't have anywhere else to go.

I feel for the son as he has a heart condition and has been off work albeit he is the only one of the two of them who is working.

I have served an s21 and am threatening court action to recover the arrears. The father is largely non responsive but the son who has now moved out assures me he is doing all in his power to convince his father to go. He also says it is causing him massive stress and anxiety which was a contributor to the issue in the first place.

Any thoughts on what I can do? Thinking around whether it would be possible for the son to get a doctors note to expedite things and also whether there is any law around what would happen if one tenant played ball but the other didnt in such a scenario.