I purchased an 5 year extended warranty for $249.00 on a 58" Samsung Plasma.  Roughly two years in it developed wide, horizontal discoloration bands that stretched across the entire screen, especially prominent during light backgrounds. I filed a claim.

DTVexpress replied we are checking with Samsung about this issue. It is a well known issue that deals with picture quality over time and thus is not covered as a defect under our terms and conditions. A technician needs to turn down the voltage setting on the TV. That solves it. We'll let you know if Samsung wants to take responsibility.

I never received a response. I emailed them again and got this response. 

We have seen many claims with this issue. It is not repairable under the extended warranty terms and conditions because it is not a defective part, but a picture quality issue that can be remedied by a technical adjustment to the voltage. That's why we sent it to Samsung, because we have opened up a file with them about the C-series plasmas. We'll let you know what they say (if they say anything). Following is a link to the terms and conditions dealing with this issue.
Under Exclusions: "Any irregular viewing quality issues displayed by any type of TV including but not limited to blooming, strobing, judder, blurring, color shift, an imbalance of back lighting in one or more areas of the TV, screen uniformity or color uniformity. Any calibration adjustments or other that can be performed by an ISF or similar calibration or technical specialist to correct picture quality attributes.

My next step was tring to get Samsung to cover the problem.  After numerous calls and online chats I got nowhere.  So I went to an local authorized samsung repair shop to "have my set adjusted" But I recieved this instead.

Estimate Charge: Unit showing screen diffusion, caused by a weak panel. Plasma panel needs to be replaced. Part cost $1140 and labor $185. So I figure it is a defective part now (which is covered by the warranty)and email Dtv express again.

They responded.. Did they decrease the power adjustment to the screen. That appears to have worked for others. Anyway, the picture quality issue you are having with the TV is not covered by the extended warranty. We do not consider it a defect (neither does Samsung apparently) as it only occurs in special circumstances (white or light background with pink shading). We consider it the normal viewing quality of this type of television as it ages. Under our terms and conditions it is considered a viewing quality issue

DTV EXPRESS does not honor their contract I urge everyone to stay away from this company and save your money