I've obtained TR60 in Hanoi and HCMC before. I don't recall needing an appt before, and today stumbled on a 1.5 week wait time for HCMC. I will go back to the website again but it points to me needing an appointment. There is no differentiation between visa type. I will get there tonight and go talk to them tomorrow at HCMC anyway in case I can't find a solution online. Searching for Ho Chi Minh here in this group are much older posts.... :-(
I don't see what the problem is. And I live locally. The prices for everyone the girls and taxi to handle it all and only 2k. Decent. The assumption always that because the negotiation took place in Thai language doesn't not necessarily imply you are being taken for a ride. If in doubt ask and stay in charge of your destiny that way.
Burning a website without supplying any evidence of what you actually did on the booking? Nah don't believe you. What was the room capacity? Screen shot. Don't have it...? No sympathy.