If a reasonable payment period has passed, you have evidence of receipt of requests for payment I would do following:
- Ask PayPal to intervene re his PP account. They probably won't though.
- Submit a complaint to Better Business Bureau.
- If the business is part of a professional business association complain to them.
- Submit a police report for theft of services.
- Consider a collection agency if financially worthwhile.
If you go the bad review be very careful to say only what is factual, and dangerous even then. Courts have awarded multi million dollar settlements on those who left bad reviews and ruined reputations.
Be polite, courteous and professional. Don't go the threat route.
I hope you get paid.
Bob