right to rent for occupier?

I have a tenant who is a British student. Fine apart from the fact that she does a lot of damage. Not fine, I think her boyfriend is living in the property with her. I have cause to question his immigration status.

The tenant has another 10 months on her 24 months ast and has only small arrears. She has a guarantor who I will be charging for several items of damage.

It seems there is very little I can do to get rid of him. I am considering reporting him to the Home Office. Their website makes it clear that the legislation applies to all adult occupiers not merely names tenants.

Oh and did I say he broke the front door down and attacked the tenant. I have invoiced £220 for the door which has not been paid. She has a social worker on her case...any thoughts?