<human>: Could you distill the essence of the text into 1-3 sentences?

I'm a barista at a local (not Starbucks) coffee shop. [This is me] 

Nearly everyday, a woman comes in and buys about $2 -$5 of product. Everyday, she has a complaint. It's our policy to remake any customer's drink if they have a problem with it. Most of the time I do this happily because I want customers to enjoy their drink, but this woman demands her drink be remade most days. Why? Usually because she didn't specify what she wanted when she ordered. She also never asks politely but instead says the drink was bad or disgusting, not because she didn't express what she wanted. She has gotten rude with me because she thought I was hiding mustard from her. Yesterday I watched her berate a coworker because of a song on the radio. We were listening to the Soul Town station on Sirus radio, a very inoffensive station. 

I've had nightmares about yelling at this woman. I get extremely anxious when she comes in. I enjoy my job for the most part, and while it's not a career or a permanent position, I don't think I should have to work in a hostile environment because of one person. My managers won't do anything about it. I would like to politely express myself without getting fired. What would you do Reddit?
<bot>: Repeat customer is very rude and abrasive. Can I say anything to her or just paste on a fake smile and wait til she leaves?