eBay complaint: eBay goes radio silence on me

I was promised a refund of the import fees plus administrative costs for importing a package bought through eBay. Unfortunately eBay managed to mess up the import process and I was not able to get my package unless I pay the import tax and the admin fee.
eBay pled that I accept the import cost and they would refund. I told them about the admin fee and the customer service agent wrote that what ever the fee is. eBay will refund it.
No that I have sent them the receipt with the tax and admin fee, they refuse to pay the admin fee.
Since a month I get no more communication from them in Them on this. They just completely ignored my emails. I have write them many times.
I also tried chatting with them and they ALL end the chat once I mention the refund.
Their strategy seems to be to ignore because “they can’t do anything anyway”. There seems to be no other way to get a hold of eBay. No escalation. No other points of contact. No office to walk to.

If ebay would not have promised me a full refund of the tax and admin fee, I would have not accepted the package and ask for it to be returned and get my money back.

How do I make ebay deliver what they promised?