Supposedly wrong item sent and buyer asking for refund

[puffinpenguin]

Hi,

I sold a pair of jeans recently. The buyer has quite rudely contacted me and said they are the wrong size. They have said..

"I would like a full refund including postage and i will return these to you cash on delivery for postage. If you are happy to do this i will leave postive feedback for you."

Now my questions are,

does anybody know what 'cash on delivery for postage' is? Is this, me to pay the return postage?

I have asked the buyer to send a photo of the tag they are referring to - they stated that the inside leg of the jeans had a SKU number that included 12 on the end of it. According to them, it means the jeans are a size 12 and not a 10(as I said they were in the listing). I referred to the waistband tag which I am sure said a 10.

I am very happy to refund the item and postage if I am in the wrong, I'm just not sure I am though.

Does anyone have some thoughts on what I should do?

Thank you very much