Coins disappeared after sold trade on marketplace

So, this week I sold 165k gold through trading in the marketplace for 23 coins. 2-3 days later I wanted to use them. When I logged my account I found out that my coins were gone. The coins did show up in my account after I sold my gold. I checked my history and only a trade I made a few months ago showed up there. the trade of this week wasn't there. So now my gold is gone and my coins as well.
I know that the marketplace is not eligible for support. But this is an issue that can't be my own fault in any way. I made a ticket about this issue but as expected, I got the answer that what I claim is simply not possible and since there are no records of the whole sale I can't expect any support.
I don't have any screenshots to proof that I actually made this trade because I never expected this would happen.
I made a legit fair trade so I would really appreciate it if anyone could look into this.

Thank you.

It's such a huge same seeing such issues taking place and having zero attention. You shouldn't ignore flaws of your website not to mention from trading...

Have you tried contacting the person that you made the transaction with?

You can't see who bought it from you. And even if I could, the whole trade doesn't even show up anymore in my 'sold' tab.