Be cordial, very cordial (put on your "honest concerned citizen just trying to help" hat) and explain that you were trying to report a suspicious circumstance as instructed and were treated quite rudely by the dispatcher. You can say that you're concerned that folks might not report the "big one" if the dispatchers don't handle things a little more carefully. I have had VERY good results approaching the folks in charge with my concerns in a very polite way. (I also make a point of writing "attaboy" letters when I see patrolmen doing a good deed or responding well to citizen calls.)