HELP! issue with bmw roadsideassistance!!

[avo8686]

I recently had my car towed because it wouldnt start.Finally after two days at the dealer they call me saying that the car was ready for pick up, so I went in and when the valet guy was bringing my car I noticed that it showed no gas plus the outside temp was showing -35F. So I called the service advisor and he took the car back to the mechanics, then after a while he comes up to me and says " the outside temp sensor is missing"

So the warranty wont cover this .They said that I had to make a complaint to bmw roadsideassitance, because they said that maybe the tow truck driver took it!!! and the only solution is that now I have to pay for the sensor!!! plus I had to leave the car at the dealer so they can check up what's wrong with the gas reading low when supposed to have half tank????

WHAT CAN I DO!!!!!??? THANKS