And what are the free return options Amazon is showing them??
Personally, I’d ask the customer. Send a message something like this -
Hi So-and-So,
Thank you for providing that screen shot. How odd that Amazon offers you a list of ‘free’ options. Did you click the ‘change to free’ button to see them, and if so, what happened?
Note - this part is commentary, don’t send this to the customer, lol. Since they are contacting you asking for free shipping, I’m suspecting they either did not click the button or, more likely, they clicked it and it said - sorry, no free return options are available for your order. Now, back to what you tell the customer…
Could you please send me a screenshot of what appears when you click the ‘OK! I’ll change to FREE’ option? Amazon sometimes promotes options that don’t apply in a specific situation, such as orders made with a third-party seller, so I’m curious what “free” options they offer you when you click the button?
I appreciate your communicating with me, as sometimes Amazon does things (and makes promises) that sellers aren’t aware of either!
Thank you,
Seller
My response gives the customer an ‘out’ if they are trying to scam you. If, as I suspect, they already clicked the button and were told no free options were available, the above response lets them claim they didn’t but now, when they click it, they see that a free return isn’t an option at all. They may thank you for your time, and send it back on their dime.
but I support fostering personal responsibility. And object to people lying to get the freebie.
Me too. 
And what are the free return options Amazon is showing them??
Rather than guess, or ask us, simply ask them. I’m betting there aren’t any. If there actually are, then we’ll all learn something.