There are no written policies for this stuff. In our opinion, if they can't provide you with a vehicle within an hour of your arrival, you have grounds to go elsewhere and try to force them to pay the difference, but that can be an uphill battle. Getting something in writing (or on video) that you have been there for X hours and they don't expect to have a vehicle for you for Y more hours would obviously bolster your case, but it's a bit of a leap of faith to go pay 4X-8X and trust that they will make you whole. No easy answers here, unfortunately.

Feel free to PM us your current rental details and we'll see what we can do for you with regard to alternate options.