Not strictly true Brandon. My husband and I have used an agent in Pattaya for the last 4 years but this year having met all the necessary requirements my husband has received his Non O retirement extension from Samui immigration with me as a trailing spouse. It was however extremely difficult and we were made to jump through all sorts of hoops before the extension was finally granted.
In reply to the OP we previously paid 20,000 baht each to the agent for 12 month extensions.