Yeah, I just got mine filled @ AirGas the other day.. What a bunch of jerks! You wouldn't believe the problems I had getting that tank filled... they were cursing, and basically saying they didn't want to be bothered switching the tank, it's a pain in the butt, they don't have CO2...UNBELIEVEABLE!....and then told me "Just Go To Absolute Fire Protection" (I think thats the name). It's on St. Nicholas St. In South Plainfield. They will fill your tank, not exchange.
I will NEVER use AirGas again.