We have many customer reviewing their products but did´nt brought them online.
Can you change their status to verify? They upload pictures of the productos they adquired.
May I know if you still keeping their (physical) invoice when they bought your products?
If so, you can take some pictures of them and share them here (or you can send them to firstname.lastname@example.org ) so we can verify their reviews.
Looking forward to hearing from you.