I paid to develop a project. He seemed like he knew what he was doing. He delayed and tried asking for more money then blocked me and disappeared. Typical scammer will get what karma has in store for him.
I am sorry to hear it, not getting remuneration for your work does indeed lead to frustration.
If it would be possible you can create a thread in "Scam Accusations" with the details of the conversations and explain what happened to be able to put a Type3 flag on their account.
This will lead to everyone knowing that the person is running scams and even non-logged in users will be getting a warning to not contact them.