Speedometer/odometer Failure problems of the 2004 Chevrolet Trailblazer

Issue originally occurring in 2008. Speedometer failed. . . First getting stuck then not returning to zero. When turning vehicle on again, speedometer would sporadically work, then get stuck, then stay on zero. Brought to 2 chevy dealerships while still under warranty (purchased extended warranty on date of purchase) and was told "the problem could not be reproduced", so nothing could be done. The problem was intermittent, as well as "service engine light" going on for periods of time . . . . Again checked by gm dealerships and other mechanics but nothing found. Here we are in 2012, I recently started driving this vehicle again as my husband was driving it and apparently didn't mind the speedometer not working at times, but, with his unexpected death in November, and my son away at college, I had planned to give the vehicle to my son to take to college, but no speedometer is definitely a problem. As I am researching this issue I am seeing many consumers have had the same experience. Why has this not been a recall by gm. There are claims of other mechanics being able to repair this issue at a pretty hefty cost. I am in no position to pay for a repair of something that should have been taken care of under the warranty we purchased, which, by the way was not cheap. Is not safety something gm has on its' priority list. Driving with no ability to know how fast or slow you are traveling is definitely an issue. I request an investigation be launched to determine the cause of this defect, which I have no doubt will result in a gm recall to repair this safety issue.