76 Gas station Jorge ripped me off. Ventura, California

I Went to this gas station at 6:27 am, bought cigarettes and and energy drink, and handed the gas station attendant 60, and to put the rest on 6. Well while trying to put gas in my truck, it stopped at 30.96. I thought, no way does cigarettes and my drink cost 30 bucks. So I went back to see what gives. He argued that I only gave him 40. but I handed him 3 20's in a way that it was easy to tell. He told me he will check the cameras, and call me if I'm right. But now it will cost me more than the amount owed to get their and back.