I rented from National Car Rental on July 29, 2011 at the Montreal International Airport.  We checked at the counter and picked up the keys late at night. After going to the lot to drop off our luggage in the car we found the car blocked in the lot.  We went back to the counter to find everything closed.  Calls to the 1-800 number told us that they had no way to contact anyone from this location and that we would have to wait until the next morning to get out of the lot.  The next morning at 7am we were waiting to leave the lot when the attendant from National arrived.  We explained the situation to him and he told us to wait and he would open the lot once he finished his cigarette. Placed an incident report with National Car Rental and received no response on a course of action.