You only have to wait a minimum of 4 days to open a dispute for non payer.
To the right of the sold item in your sold list there is a drop down, click resolve a problem and follow the prompts.
4 days later to the second or longer if they still have not paid you can close the dispute, issue a non payer strike and get your FVF refunded.
Then you are free to relist or offer to the next bidder if there was one and you are happy with the price.
