Best manufacture response

Bought a 2006 Chevy Duramax. At 35000 miles the dealer said it had a bad Glow Plug and recommended we replace all 8 for $900.00. It was supposed to be under warranty but they said we had to pay it and then collect from Chevy. They didn't pay and I wrote to people as high up as I could. Now I tell every one what a POS Chevy makes, don't buy one and I was driving truck cross country at the time. I think that by word of the CB radio and on different forums it has cost Chevy thousands of dollars just for not paying 900.
I don't recommend a Chevy to anyone.