Summarize the seller communications and the static tracking behavior, then open formal mediation by contacting ebay buyer protection and ask them to verify carrier logs and merchant fulfillment records. Request that ebay push for seller proof of delivery or, if none exists, to authorize a refund under buyer protection. Ask for a single case handler and an estimated timeframe so follow-up is streamlined; this focused approach helps ebay move from investigation to decision without prolonged back-and-forth and avoids unnecessary escalation steps.