Where exactly is this leak, you need to provide more information but more than likely the managment company should pay for the repair but the agent should be looking after this, that's his job after all. With respect to the balcony, the managment company owns it, the tenent has exclusive usage to it, it would be in the managment companies best interest to effect any repairs and set a precedent for the future with respect to who maintains the balconies as should someone choose to paint theirs pink or refloor it with tiles you will wish you had.