How should I handle this disrespectful behavior?

So, I have an an aunt (my father's sister) who lives alone (she is almost 60 years old) near my home. My father has an amazing relationship with her (of course she is his sister). Whenever she needs to get some stuff done (such as some house repair, or grocery), she would call me to help her with that. However, she has gotten really comfortable with doing this. Now, I do not have a problem with helping an elderly relative. However, she has started to treat me like a servant (when in fact I am being nice to her). She orders me and talks to me harshly. She looks visibly angry and disgusted looking at me, as if she bought me as a slave. All this is really disturbing to me and I feel disrespected. I can not just say no to helping her because of my father. I just want her to treat me like a human being sho is doing her a favor. Any advice would be appreciated in regards to how should I handle this, thanks. 💖
How should I handle this disrespectful behavior?
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