GameStop review: customer service

An employee named Alyssa at the gamestop at the Legends in Kansas City would not sell a M Rated game to me even though I am 18. My younger sister was holding the games for me because it was black Friday and my hands were full with bags from other stores. Alyssa said that because my sister was holding them I could not buy it even though I am 18, I have my ID, I am paying for it, and I am the one purchasing it. She also was very rude, inconsiderate, and handled the situation extremely poorly. I have been a lifelong customer but I would not like to shop at GameStop again because of her.