2. Residents (preferably Thais) might write to the Land Development Department in Phetchaburi, asking them to enforce the law that full Development licences should be displayed prominently at Palm Hills.
Again Alain De Rocker might be able to help you in this.
Finally, until you see the Development Licences or hear from me that they and hard evidence exists,
3. You might decide to pay nothing at all for Public Utility fees (other than 4 or 5 baht per unit of water).
This would be eminently sensible in my opinion.