Refueling

I just bought a 2006 Pontiac G6 convertible with 10,500 miles. V6 engine. I cannot seem to get gas in it. I have been to 3 different gas stations and its the same thing. The nozzle shuts off as if the tank is full. I get about.50 cents worth for each squeeze and then "kachunk". I move it around, further in, further out. Squeeze less, squeeze more. No luck. I wrestle with it until I finally get about $10 bucks worth of gas and then give up. Havent been back to the dealer yet, its still under warranty, but in case its something simple, thought I would check here first. Thanks for your time.