Today, April 30, 2017, at 7:26 pm, I went to get a large diet coke and a large Dr. Pepper with cherry. I got to the window, give my card to lady at the window. She gives my Dr. Pepper and then my Diet Coke, but my Diet Coke was a medium. I told her "Hey, I ordered both larges." She, very rudely/defensively, says "I rang you up for a medium." I wasn't trying to get a large for the price of a medium. I just wanted what I ordered. I would have been fine with her voiding the order or paying the difference. I was kind of speechless at how rude she was. She then said "Have a nice day" in a rude tone. I've had several less than good customer service incidents at this particular Sonic, but this really confused/shocked me that she was so rude about it. No apology, no offers to correct it, nothing.