A a non-o visa applied for at immigration based upon retirement is here.
https://www.immigration.go.th/wp-content/uploads/2022/02/9.FOR-RETIREMENT-PURPOSES-50-YEARS-OLD-NON-O.pdf
I think somebody at the embassy gave you some false info. It can still be done online according to their website. https://thaiembdc.org/2020/11/17/nonoretirement/