If I have had a bad transaction, non-payer, goods arrive damaged, and have contacted the other party and they will not work with me to resolve this, I leave a negative. If I get one back, I respond with a calm and clear reply.
If you do this then other buyers or sellers can see who is at fault.
A negative is not nice, but it is only one comment on an online site, soon lost and diluted among the positives which follow.
Keep calm and have fun. ๐