Keep in mind that you are applying for a 30day extension to a visa exempt entry.
This is tourist type extensions and most tourists would not have a lease.
A TM30 should be sufficient.
You state that Jomtien required a rental agreement was required for a 30 day extension? Did you provide Jomtien with a TM30?
BTW nothing surprises with both CM and Jomtien.
Both rubbish offices.