The cancel transaction request can only be initiated by the seller, and once sent, the buyer needs to agree to cancel it before the FVF are credited back (if they don't respond, you can close the request manually after 7 days to receive the credit).

Your choices are basically to send the request, or open an unpaid item dispute.

The cancel transaction request will finalise the transaction as soon as the buyer agrees, and they will be able to leave feedback etc.

The unpaid item dispute can be opened four days after purchase, then closed for a FVF credit (if payment is not made) another four days later (so, at least 8 days in total). The buyer receives a strike on their account, and they shouldn't be able to leave any feedback.

The choice is yours, though.