A: What can you do? You can go to arbitration and argue about 'good faith'. The RTB publishes a policy guideline found at http://www.rto.gov.bc.ca/documents/GL02.pdf which identifies how an Arbitrator should determine a case about good faith. It is up to the person making the assertion to persuade the Arbitrator that the motive of the person is in question and he doesn't really intend to do what he says, which is always a tough go. The RTB guideline proposes a two-part test: 1) the landlord must have a genuine intent to use the premises for the purposes he states on the notice and 2) there cannot be a dishonest or deceptive component in the primary motive.
I always found the good faith intentions of a person hard to argue against, if only because when challenged the person becomes even more resolved to do what they said they were going to do. In the end, your case will rise and fall on the persuasiveness of the parties making the argument and bringing the evidence. Good Luck. Let me know how it turns out.