If you don’t mind 10 minutes on the bts there Is a great Indian near on nut station . “Om Ganesh” on sukhumvit 50 about 200 meters from the station. One of the tastiest I’ve ever had.
I got married in June , tried Phra Khanong , lak si, bang rak , Bangkok noi, and a couple of others i forget. All of them said that we must make an appointment and we were told 2-3 months . Ended up paying an agent 4k who got us in at Bangkok noi 3 days later. Got the certificates after about an hours wait.