How to get back at a company where you voluteer for after being top person?

So pretty much I volunteer for a fire department in NJ, as a firefighter our department. lets say the dept is called XYZ rescue, so XYZ rescue has been getting into trouble with the state and the 911 system for not having crews and drivers to respond on calls. I have recently gotten the top responder of the year, for being most active and completing all of my requirements. So one day as its a volunteer we dont take shifts we just come to the firehouse for calls. so one day XYZ rescue gets a call for a overturn auto with person trapped. for once we had a crew and the truck got out, but being a EMT also i responded with my personall car to assist, no one told me to come but being certified in both rescue operations and medical treatment i took the liberty to respond with my own personal car, when I wasnt suppose to but everyone responds with their personall vehicles to scenes and I thought me doing it one time wouldnt matter, but it did now they are lowering my ranking after that one small incident. Ive been told by the chief and many other officers in the firehouse that im a great asset to the dept. many people have been in the same situation as me and have resigned from the dept. they dont offer anything for responding all the time ive never got a pat on the back ive been told im a good asset but thats about it. now im debating on quitting also but am not sure what to do. i want a way for the dept to realize what they are loosing. and I know payback is not good but i want a way to show the upper level guys what they are going to loose because I am not replaceable ive been on pretty much every call because my job is very lienient and lets say the average person makes 100 calls a month i make about 400 calls a month. Please someone give me advise on what to do. Thank you