Underbody Shield problems of the 2002 Nissan Pathfinder

I went to have my oil change at the garage,I told the mechanic I could hear a hissing noise from under neat,like a noise from the muffler. When he checked he said the catalytic converter was split open,he told me to bring it to the dealer,it should be covered under the pollution control. When I got to the dealer he checked it out and told me ,it was called a tube or a pipe not a catalyitic converter not covered under warr. ,but Nissan sold a patch to repair this,at the time I had around 44,528 mi. On my Pathfinder just over the 36,000 mi warr. So I called Nissan to explain the problem and told them I was a loyal customer after bying 3 Pathfinder and my wife 2 maxima,I don't seem to have gotten anywhere but sorry. I was told that a regional rep. Was going to call,but we never connected. The service mgr. At Nissan told me they were aware of the problem,that I was not the first,I hope this will do some good maybe get my money back. Repair work done on 6/18/05. Thank you.