There is a private international visa processing company called VFS that process the DTV + other vidas for the Thai embassy in Kathmandu. They are located in the 3rd floor of a new shopping mall in Thamel area.
VFS handles the applications for the DTV in Nepal and they are a shower of ( Redacted ) and known to be overly pedantic. Someone has to pay for that shopping mall they occupy in Tamal.
Once I saw they had their grubby little hands in the application process, I looked elsewhere.
Just interested to know if you actually contacted the Embassy of VFS.
The ask:thailand community, consisting of multiple Q/A groups with over 100,000 members, powers this platform. It is not an official government resource. Our members actively contribute to this resource, and while we strive for accuracy, we cannot guarantee its complete reliability. Assistance to travelers is provided as a community service.