I used the platform via eBay classifieds Germany and contacted them. I was informed that the case was being processed and that the seller would have time to respond (even after the deadline). Since I had already contacted the seller, I wanted to send this communication to the payment platform. It was not possible to make further contact. I was redirected back to eBay Germany via a link and asked to contact the seller or the payment platform. There is only a "no reply" email address for this payment company.
In addition, I was initially contacted in Dutch, then English, and only then in German. It can be assumed that the majority of eBay Kleinanzeigen Germany's customer base speaks German, so why doesn't the payment platform tailor its customer information accordingly?

Finally, the refund was initiated. However, the money has not yet been refunded (22 days after the purchase and 14 days after the deadline). This clearly works better at Vinted...
During this time, the payment platform is working with the customers' money.