Ebay allowing a **** to happen without confirmation on my side what's going on and letting a transaction be refunded on a ****

I'm absolutely blown away how EBay has let this man **** me . I will never use your services again for lack of service and not confirming from both parties first to confirm his side of the story !!! Yet you just reversed the transaction and allowed him to **** me via PayPal PayPal !!!! I put an add on eBay for a Marvel acc . Christopher Gallagher contacted me to purchase the item and paid 290$ into my paypal acc. We then exchanged details for the acc over "Line" he received everything and was happy !!!! Without questions he changed the email password and the games login details after I received the payment via PayPal . When I saw the amount owed to me put into the acc I thought there we go as easy as that being a first time "rookie" on eBay and PayPal I didn't see that after that you need to do a shipping order set . As I wasn't fami**** with my first time selling on eBay and knowing the amount owed to me was put in my PayPal we left it . More than 15 days passed and the money hadn't cleared it said "pending" so I contacted PayPal and they didn't give me an accurate answer to why this was happening and then they buyer must have been informed about this.( 20 days later he reversed the transaction and was refunded) As he has been on eBay since 2014 he then opened a case against me saying I didn't give him the correct logins for the email and game and I'm not responding to any messages !!! There are no recorder or sent messages to me about this and eBay refunded him taking the 290$ back and having the game now. Absolutely shocked and disappointed!!! I mean if I sold something on eBay and I didn't receive the correct email and game logins I wouldn't wait 20 days to report it I would have done it in the first couple of days unfortunately the **** worked and ebay isn't hearing my side and allowed this ***** to do his thing.