If you mean they are a current bidder but the auction has not ended click on where it says number of bids on the actual listing and on the next page you'll see their ID. Click on that and there's a contact link on the next page.
If you mean the auction has ended but the highest bidder has not paid you will be able to cancel the transaction due to non-payment after 4 days.
**peaseblossom**
Mentor2 weeks agoIf you mean they are a current bidder but the auction has not ended click on where it says number of bids on the actual listing and on the next page you'll see their ID. Click on that and there's a contact link on the next page.
If you mean the auction has ended but the highest bidder has not paid you will be able to cancel the transaction due to non-payment after 4 days.