Non-payer, likely a troll, how do I stop this?

I am awaiting payment for a bike I sold on eBay for £1100. I put a reserve on it as it is an expensive bike. The person who ordered it has zero feedback.

https://preview.redd.it/4ebev6qgot6e1.png?width=614&format=png&auto=webp&s=933c5edea9f08466f1d3791874d38d951878f0ae

I am sure they are a troll because they are not communicating, and they have no intention of buying it. I am now out of pocket for eBay fees of over £50 due to the reserve.

How do I stop this from happening again? Will eBay charge me regardless of the non-payment?