Warranty of van

I bought a new 07 Nissan Quest from Lithia Nissan of Fresno. At the time the closer sold me the warranty upgrade wich was 100,000 bumper to bumper. At 94,000 miles we took the van to the service center for an engine knock. They verfied the knock but said that nissan would not cover the repair because we were over miles on one of the oil changes. They said they called nissan, and nissan requested pictures of the engine. They said they would take the pics. and send them to nissan. If nissan decided not to cover the engine repair, Litha would charge me $450 for taking the pics. I had a bad feeling the warranty would not be honored, so I declined the pics. None of this made any sense to me. Litha verfied the problem and the van is under 100,000 miles. The warrany should cover the engine. Don't go to Litha, and don't buy a nissan.