I would go down there and sit at his desk untill he delivers you a key. Did you get it in writing?? If not bad on you. Always get that type of stuff in writing from sales people. They will tell you anything to get you out the door. If you don't have it in writing he doesn't need to deliver.
Either way sit at his desk, don't make a big scene but be a pain in his ass. I have seen customers do this before and it works, other thing to do is contact the Sales Manager and then if he doesn't do anything go to the General Manager, work you way up the later. Thats all you can do....Good luck!!