Lady taking advantage of me

So I sell a brand of clothing part time for babies, children & women. My mother’s co worker expressed interest in a top and a dress tops I was selling. She ordered them, and they just came in yesterday. She texted me this morning saying she hates the dress and the top, and they look nothing like the picture, (mom got the exact dress and loves it, it looks the exact same) and said she wanted a refund. So, fine whatever, it’s her full right to a credit so I explained to her how to send it back herself.

Since she bought these items on a sale, I can only give her credit for the online website.

The commission I received from her order was $4.08

She wants me to send these back, she dropped them off to my mother at work and told her I agreed to send them back (I didn’t) now she is leaving me responsible with a shipping charge that will cost more than my commission, and I’ll lose my commission. She refuses to send them back herself, this was all explained to her beforehand.

I just don’t know what to do