If you agreed to ship to their destination, you should be able to manually send them an invoice.
https://www.ebay.ca/help/selling/selling-getting-paid/issue-invoice-combining-payments?id=4139
Those are instructions there. Two things to consider:
1 - Don't send anything surface or with the cheapest option. It will take forever, which will enable them to open an INR. Even if they aren't looking to scam you, they might open an INR because they think the item is lost in transit. Tracked Packet should be fine depending on the country.
2 - When you send them the invoice, select a generic economy service. eBay's shipping estimates do not account for delays. Unless your buyer is paying for a service with a guaranteed shipping date, a delay with something like Tracked Packet might enable the customer to open a false INR.
(I don't suggest you game the system and choose something with a 90 day deliver estimate, as that would be dishonest since it could prevent a genuine INR case from being opened. I suggest using something with a similar but slightly longer time to account for delays. Similar to how people use the generic Economy Shipping in Canada that is 18 business days as a subtitute for lettermail which Canada Post quotes at 9 business days but not guaranteed.)
If you didn't agree to send to a different country ahead of time, I might consider cancelling due to a problem with address. It really depends on how big of an item this is. The reason is that you have to consider liability, especially if this is a big item. It's not just about getting the item to the person, but dealing with the possibility of return extortion. Meaning, the customer knows that if they claim the item is not as described, you have to cover the cost of the return label. If a return label is going to be expensive, the buyer can use the threat of a return to extort a partial refund. I am not saying that will happen here, but when you agree to send internationally, you have to consider that liability.
An example, I sold something this year that was almost 20KG and very fragile. It would cost $50 to ship it regionally in Canada to Ontario or Quebec. Because it required a signature, it would cost almost $200 to ship to the USA. Had I received an offer for it from someone regionally, I might have sold it for less than to a buyer from the USA because in a worst case scenario with a USA return, I would lost $400 in unrecoverable costs (original shipping label + return shipping label). Regionally, I would only lose $100. Because of how eBay's return process works, that is something that always has to be considered in these situations.
