okay wait just a minute,
@Andrew *******
If you are now on a Non-B visa EXTENSION from the immigration office, you don't need to get an O visa to apply for a "retirement visa",
all you need to do is cancel your current extension based on employment and immediately apply for a new extension based on being over 50 (retirement).
NOW because you're NOT getting a Non-O visa, just changing the reason for your extension from one based on employment to one based on being over 50, you MIGHT, as in you may be able to use the 65K baht a month in monthly transfers from the previous 12 months
you need to go to your immigration office BEFORE you cancel that Non-B extension with documentation from your employer and SEE if they will take monthly transfers for you to meet the proof of funds to change reasons for an extension from one based on employment to one based on being over 50 (retirement)