I used to go to this store often for milk tea, until they recently hired a new (male) employee who completely ignores my request for no sugar (health reasons).
I always order tea with "no sugar", but he still adds sugar to my drink. I stopped him on many occasions to prevent him from screwing up my order.
This time, I was in a hurry and forgot to check and guess what? He screwed up my order when I'm not watching.
Not sure if he's doing this on purpose or he's trying to screw the store over. I'll tell the owner next time I see him...