Amazon.com Got kicked out of selling , Internet

After not being able to secure a teaching job due to work related problems, I turned to sales.  I've been selling items through mail order for years selling DVD's and used video games, and have never had issues apart from the PO destroying a package and refusing to take responsibility. I have sold on Amazon for years, and just got kicked out of selling because of an unfair negative feedback.  

A new customer to Amazon made her first purchase with me, and I refunded her entire order because I noticed the movie she ordered was a promo disc. I sent her a detailed message as to why I refunded her order. She asked me several questions about how her money would be refunded to her credit card, and I explained every step of this in plain English to her. When she was assured that her credit card had not lost her $8, she then promptly left me negative feedback (including poor customer service, no communication, and poor shipping time). Amazon upholds her right to leave unfair feedback, and I could do nothing about this. The final straw: because the item turned out to be a promo disc, I was banned from selling because promotional items are not for sale. End of Story, and end of my relationship selling on Amazon. 

SERIOUSLY??? I refunded this customer's entire purchase because I didn't realize the item was a promo when I stocked it, and once I caught the mistake, I had no intention of selling it, otherwise I would have sent her the %$&$ disc and she never would known the difference. But now I am banned because I tried to stop the sell of a promo disc and gave this customer all of her money back? As of right now, I am still within the window of delivery for that transaction, but yet she leaves me poor feedback for shipping time? I answered every question she had through Amazon messaging, but she leaves me poor feedback for communication? I gave her a complete and instant refund, but she leaves me poor feedback for customer service? 

Amazon obviously does not care about small business sellers.  I do this for a living, I feed family of three, and now this.  I am devastated, and this is to put it nicely.