Nissan Pathfinder 2005 fuel gauge malfunction

I have a 2005 Pathfinder that I bought used with 23,000 miles on it. About 3 months ago, the fuel gauge went out of whack, telling me I had no gas even after a full fill up. The DTE tracker also showed empty. In my research I have found that many other Pathfinder owners have this problem and Nissan issued a recall for 2006 to 2008 models. When I called about my vehicle, they said it was not included since it was 2005 even though it is clearly affected by the same problem as those under the recall. They told me to take it to the dealer, which I did, who wants to charge me to diagnose (I already know the problem - duh!), and of course, parts and labor. I took my car home in disgust, refusing the repair for something they should be responsible for. How can I take this to the higher ups at Nissan or am I SOL?