Attached is the official eBay link that for sending a request to appeal ebay charges like an eIS bill or duplicate/secondary charges for eBay labels. It will connect you via your user name and you can submit any documents you have as back up.
https://ocswf.ebay.com/mudcwf?deptName=CollectRemitRefund&fbclid=IwY2xjawMUlmxleHRuA2FlbQIxMABicmlkE...
To appeal duties paid via Gov of Canada customs shipment via courier:
https://www.cbsa-asfc.gc.ca/sima-lmsi/rrd-drr-eng.html
