Whats everyone's take on tire warranty.

I have a 2 year old S Class, 23K miles and recently had an alignment at a local Dealer. I had to take it back - it still pulled. Second time they technician/service advisor said the tires were defective and 2 new tires would make it good as new. I told the dealer that I was sure tires defective were covered for 4yr /50K but he was adamant that there was no warranty on tires. I checked my manual and it states pretty clearly that tires are covered for defects, so I called the service manager. He agreed that tires were covered for defects, and he would call back after talking with service advisor. Needless to say he has not called back despite repeated messages left.

Any chance dealers are on some kind of incentives to disqualify warranty work ??