Trendyol Lost My Returned Item and Has Not Issued a Refund

I got two different items from Trendyol. I got one thing that was wrong, and the other one didn’t fit, so I had to send them back. While we were handling the return, it seems the refund codes got a bit jumbled. I followed all the return instructions, but Trendyol lost one of the items I sent back and didn’t process the refund. I was trying to figure out how this happened, but their customer service didn't give me a clear answer. I feel disappointed by the poor communication and lack of accountability. It's really annoying to deal with all the trouble of returns and still not have the problem sorted out. I hope Trendyol will acknowledge this mistake and give me the refund I'm due.