I am hestitant to tell people what to write because I don't think a form letter response will do good. I think everyone who chooses to write (and I hope many of you do) should say things along the line of what has been said in this thread.    Asking them to please reconsider their decision is not a bad start.

Here is an outline - put it in your own words and actions:

a. You are unhappy with the decision to eliminate the show. Explain why.

b. You are unhappy with the company/individual for supporting this decision because they are either an underwriter or a member of the board.   

c. Ask them to do whatever they can to reconsider.

d. Let the them know the consequences. Tell them what you are going to withold - donations, you won't support or purchase their product, you won't listen to the radio station, no more sex, you are going to hold you breathe and turn blue, etc.   You can think of your own words and actions!   Let them know you are angry and you are going to back up this protest with action. You are the consumer and you are going to take your business elsewhere.