Update for anyone who may stumble upon this post in the future - I’ve been hung up on via text chat with an eBay customer service agent, and the issue has not been resolved. The agent continued to dodge my question about why the initial postage quote was so incorrect, and said there’s nothing to be done since the return has been closed. I find this to be a predatory system leaving me as a buyer feeling stranded. A very negative experience and I’ll be reluctant to shop with eBay again. Cheers everyone