Ok, I also found it a hard way when I was told to pay for the return. It is a subtle trick that eBay uses to help the sellers regarding the returns.
When you start a return process, this is what comes up.
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If you click "changed my mind" or "just didn't like it", the cost of the return is on you. I did that since I could not see a "faulty" option and was given the instructions to return the item by purchasing the postage myself that seemed unfair to me.
I quizzed the eBay support and was told that in order to get a seller to pay for the return of the faulty item, I need to expand by clicking "show more"
When you click show more you are presented with more reasons as to why you are returning this.
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Now with wine, my suggestion is to click "Doesn't match description" (ie you think it is medium bodied vs the description of full bodied etc)
Then you will get a prepaid return label.
That said if you are eBay Plus member and returning within 30 days - the return should be free as VM is an eBay Plus seller.
I would suggest to get on eBay support and demand a prepaid label.