The usual practice if there is a strong risk of losing the deposit is not to pay the last month's rent. Sadly I'm in that situation myself as the landlord (thinks we don't know that the agency he runs is actually renting us a house his wife owns - and pays no tax on!), after dithering on repairs, not sending a proper renewal lease after the first year, refused us a rent book, denied us the right to claim rent relief taxback (he even had the cheek to tell us we were not entitled to it), and hasn't maintained the place in years, is just such a greedy Ba****d we don't trust him to return the deposit.