I'm trying to understand what happened here.
If you (OP, or whoever you already represent here) did not request payment in ethereum, how the exchanger knows what your eth address is?
Is it 0x4c15B9B6E6177f20E745254758ed84b3e33a447E really belongs to you, I mean do you have access to funds on there?
if that entire amount still remains in your possession, this case cannot be characterized as fraud.
something completely different if they behaved unprofessionally and if they have caused you many complications during one round of exchange.
I think with you, it is shasan's duty to ask this. Based on the OP's screenshot, this customer has sent an address to email to verify the request via telegram. Maybe the customer here doesn't understand that ETH is also accessible as long as he has the private key regardless of what network the address is generated from.
Just my thoughts.
Sending returns in other cryptocurrencies that are not written on the customer's order in the platform is a bad solution, especially since the deal is also done off-platform.