About a year ago, I ordered a moderately-expensive Nolan helmet from an established eBay seller with excellent feedback. The helmet I received was the right size, right model, but wrong color. I contacted the seller, explained the problem, and requested a return shipping voucher. No response. A few days later, I tried again. Silence. After more than ten days had gone by with no communication from the seller, I contacted eBay. They requested pictures of the helmet and the package it came in, which I supplied. They said they'd contact the seller and arrange for a return.
A few days later, eBay reported that they'd not heard from the seller, and had given them a response deadline of approximately 5 days hence.
Following passage of the deadline, eBay contacted me to say they were issuing a full refund, and I need not return the helmet.
The day after the refund hit my account, I received a message from the seller: "Hello _________. We understand there may be an issue with your eBay order number XXX-XXXXX. Please explain the nature of the problem and we will investigate...blah, blah, blah." I responded with "No thanks, the issue has already been resolved to my satisfaction." That was the last I heard from them.