You do not need to use a QR code and you - certainly - must not change any address on the whim of the seller.
Sadly a good maxim is "Do not take advice from the seller"
Simply open a case for "not as described" [or whatever] from the purchase in your ebay and add a photo.
The seller will send a label through the case [if he does not, or messes around] escalate to eBay after 4 days. The label will have the correct address held by eBay. Simply pack it up carefully and send it off. The eBay label has tracking and when shown as delivery or attempted delivery the seller has 48 hours to refund. @ang_ac_lpqy67