the agency chargé you $900 to take care of it all, even front the funds in a Thai bank account they open in your name. Easy peasy for someone that is lazy or don’t understand the process. Just saying it can be done
I’m using an agency for my marital visa, $900 incudes EVERYTHING (paperwork, funds, open Thai bank account in my name) the only thing I provide myself is marriage certificate from my country.
Not sure about DTV but should include all, because they have DTV service.
Just checked and they charge 30k baht for any kind of visa needed.