Hey guys new to eBay . so I had a watch up for sale that I sold now I put the watch up for sale that was my late pops watch which due to circumstances I had to sell, now I took the watch to a place a couple years back and they told me what it was so only going off their info I’m no watch expert  now I put it up for sale/auction on eBay and had a guy message me asking for authenticity and paper work I clearly stated I didn’t have any hence the price so he was fully aware, also told him I took the watch to a place a couple years ago and am only going off what they told me, now the photos I posted of the watch are clear as day and multiple pics of watch, I also stated in my ad the watch had been sitting for a very long time and also before posting ad I put my returns as I do not accept returns, now buyer was fully aware of what he was buying, I sent the watch of obviously gave tracking numbers to him. 

he later received the watch and took it to his watch guy they had a look and he said that the watch is a replica and doesn’t work and would like to be refunded.

I spoke to him about it and clearly stated he knew I had no paper work for it hence the price, I had told him it had been sitting for a very long time also I don’t accept returns, once the watch is sold it’s not my responsibility, now I know if I was in his shoes I would feel the same way but he knew what the risks was when buying this

watch.. also I did not know the watch was a replica I was only going off what I was told, I’m know expert and didn’t have time to get it checked out, if I had of known it was a replica it wouldn’t have been sold! 
How do I come about this situation?i?

Now I have offered  to give partial refund the whole amount I got after gst, he then said no he wants full amount I’ll be out of pocket then, will eBay refund me the gst or what is the go?

Now I’m new to eBay and am only trying to understand and resolve this problem the best I can, where do I stand with this situation as everyone says customer is always right supposedly but as a seller do I have the right to refuse refund, partial refund fair enough? How do I contact eBay about this situation?i