Car rental question? I am fed up?

I rented a car from a local rental company in my area for my vacation for approx 8 days,I told the lady at the desk that I needed to return the car after hours due to my schedule she said there was "no problem there's a drop box" I said okay and went on about my vacation as planned.Tonight When I went to return the car?!? NO DROP BOX.. Only a mail box!? NO ONE is answering the "after hours 24/7 cell phone" and THE MESSAGE BOX IS FULL.. So thus I am sitting here @ 2:17 AM completely exhausted and this place doesn't open until 7:30 am!? My personal vehicle is there and no where to leave the freaking keys.. what would you do? how would you go about cursing them? and would you?