Cinemark review: concession employees and services

Hello,
I purchased tickets just fine, and then got in a very long line and waited to buy concessions. I had 2 concessions gift cards that each stated "1 free junior popcorn and 1 small soft drink". After patiently waiting in line I finally got up to the cashier. I gave the cashier my gift cards and asked for 1 coke and 1 water. She responded "I can't give you a water, I can only give you a soda." I looked at the prices on the board, and I responded with "a small soda costs $4.25 and a bottled water only costs $4.20, so I'm actually saving you $0.05 by getting a bottled water instead of a soda." She replied "It doesn't matter, you can only get a soda." I was confused, so I asked "if it's less money, why can't I have a water?" She rolled her eyes, sighed, and yelled down the row for her manager to come over. I explained the situation to the manager, and again explained that I'm asking for an item of lesser value than the gift card. He told me that they can't give me a water because "there's no button on the cash register for that." At this point my movie was starting, and I was very frustrated, so I decided to just get the soda and buy the water extra. I was extremely displeased by this interaction, and was treated poorly for just trying to get water instead of soda.