You should be able to change your 'ship from' location in your account settings so that should change the address on your packing slip...hopefully. But I suspect that won't affect your VAT issue.
As I'm sure you know VAT is a sales tax, not an import tax. From July 1 eBay is required to charge VAT to EU customers. Is VAT already included in your pricing and if so, is someone paying that tax to the EU?
I'm really not familiar with how it works if the product is coming from the EU but this page might give you more info.
https://www.ebay.ca/help/selling/selling/vat-obligations-eu?id=4650