It might help if you gave them a link to this thread. Philips customer support tried the same crap with me, trying to deny and dismiss the clearly visible color banding on my HDTV with the Computer mode. After the constant back and forth I got fed up, so I made public polls and threads (with the same sample images I had given them earlier), and gave them links to them so they can read "other people's opinions". And EVERYONE noticed the flaw right from the start. The tone of the conversation changed quite rapidly after that.
In reality, I think they knew perfectly well what was the matter, they just tried to give me the run-around. And in the end, they admitted the flaw. They probably gave up because they realized that the bad PR wasn't worth it for them. Then again, they never fixed the issue, either. Even though they said they'll forward it to the firmware team. Not that I was surprised, really. They were quite pathetic at fixing things. Usually they only managed to make things worse... Well, never gonna buy anything from Philips, anymore.
Ps. I also gave them
THIS link. They said "they couldn't open it".