Father & Son Deli

So, I have been a loyal customer there for a while now but this experience really turned me off. We normally make a lunch order, two or three sandwiches, but this experience wasn't as pleasant. Today I went in and I had to pay for three items seperately and I got nothing but attitude and rudeness. The "owner" said to me "are you serious?" when I asked to ring separately. I do understand that credit companies charge per transaction but I've never been told so rudely. The "owner" felt the need to harass me about how he's getting charged per transaction and told me "he can do whatever he wants since it's his store". So, I paid for the sandwiches that were not mine and told him I don't want my sandwich and he told me "Good, I am losing business on customers like you..." Now, I am not in customer service but.. I'm not sure that was the best way to handle a customers inquiry!