Address for the postmaster General-write him directly!
Postmaster General John E. (Jack) Potter
475 L'Enfant Plaza SW
Washington, DC 20260-3100
I suggest you mention that this a nationwide problem.
Roughly up to 50% of the Post Offices across the country have been overcharging for over a year now. They are charging parcel rate for all padded mailers
Site that there has been overcharging discovered in
Tell him that it has gone on entirely too long, and the nationwide problem needs addressed....right down to each and every window clerk. Tell him that is has been discovered numerous times that often the Postmaster/Mistress was not even aware of the correct charge. There is proof of that in several threads...see link below for threads
The link below shows all of the postage threads and the States the members are in that have encountered problems in the last year.
Here is a link that might be useful: Postage threads just at The Seed Exchange