CEFCO Convenience Stores review: employee

I come in here every morning on my way out of town and purchase a coffee. Every day all size coffees are advertised to be .99 and usually there aren't any Large cups available, but for certain there aren't any extra large to be found. The girl that's working is a black woman, probably early thirties, I see her alot. She's never very personable, doesn't greet me at the door or at the register, doesn't even look up at me at either point, I've never seen her smile, or wish a customer a good day, I've not seen her even PRETEND to want to be here one time in all the mornings I've stopped at this cefco.
Today, however. I asked if there were Extra Large cups and an eye roll was my only reply. Then when I asked if I could use a fountain cup, for my already poured coffee because my cup was bent as were all the rest and I didn't trust the lid to stay on properly I was informed that she didn't know what to tell me, the kids were one size fit all and with another eye roll asked "so was I gone' buy the coffee or not."
I don't know if this is just a terrible company to work for or if her mom just died or what the case was to explain this TERRIBLE excuse for customer service today, but I'm one hundred percent going to go MILES out of my way to stop at a different location and plan to see to it that everyone I know does the same as well from now on.
I've never been treated so poorly, or with such disrespect by someone who is very literally getting paid to do nothing more than adequately preform duties in a CUSTOMER SERVICE position.