Tenants sub-let garage for a mate to live in

I don’t know if this is where I can ask a question or just comment on a particular article.
My daughter owner occupies her unit in a block of 8. The renters in the unit above her have a mate living in their garage. It is immediately below our daughter’s apartment. The garage door is being operated multiple times a day and his cigarette smoke permeates her bedroom. She has informed the agent but nothing has happened in 3 weeks.
What is the legal position of someone living in a garage?
GP