You normally go through the correct process,  where the buyer lodges a case,   you send a return lable (via Ebay case),  buyer returns item,  than refund is made if legit.

Sounds like you just sent a refund, without going through the formal channel.   Or the buyer had lodged a case,  but you didnt respond correctly.

You certainly don't leave such a buyer positive feedback as you have done

And a feedback comment that makes no sense asking for help is not going to achieve anything