Government vehicles

I have tried to find out the answer in the contract but not finding what I need to know about government vehicles assigned to route. The assigned vehicle has been destroyed and another vehicle has not been assigned to route. Having to wait to see if vehicle is available every day. Had issue with vms giving me broke down vehicle that came in to be repaired. Sat for an hour and a half to get vehicle that had grinding brakes so bad I thought would catch on fire. The next day was given same vehicle that broke down before I got a mile down street. Was then picked up and took to another station for llv and it ran out of gas before could get to gas station. Waited for over hour to get gas and then in the middle of rain storm wipers went out. At 230 was at first stop on route and told them I was done for the day since every vehicle was not working. Looking for answers on how long to wait and how many broke down vehicles they can give me before I can refuse to keep changing and reloading and getting no where???