@Craig *******
you were on an extension of stay based on education from a school in bangkok and were told you couldn't change the reason for you extension to one based on being over 50 (retirement)?
As long as the extensions are from the same office, you can cancel one extension (based on education) with paperwork from your school, then immediately apply for a new extension (based on retirement) by meeting the proof of funds and submitting the correct documentation.
People are allowed to change the reasons for extensions from education to marriage or retirement