Cheap Car Rentals in Charlestown, Boston

My flight got in late and I was going to miss the closing time of the car rental place. After two unsatisfactory calls to National trying to see if they could stay open later to wait for me, I made a third call and was assured that the place would stay open an extra hour as my flight was late and that was their policy. When I got there (absolutely within that hour), they were closed and I was stranded, having to find alternative transportation and never got that rental car from National.