NZ charge nearly 40,000 baht to apply there. I think Laos does them for 10,000, but it’s probably going to cost you more than 2,500 baht to get there and stay during the processing time.
You are referring to a paid teaching position that requires a Non B visa and security clearance and stuff. Completely different to what the OP was referring to.
I’m sure “Thai Legal International” know what they are talking about. That’s what you’d need to do your job.
A Non B stands for “business” visa. It’s for employment. It’s where a company employs you (and pays you) to work for them.
A Non O (volunteer) visa is for people that “work” at an institution but don’t get paid. A work permit is still a requirement to do that though regardless that you’re not getting paid.
It’s actually probably the best suggestion. Contrary to popular belief most offices will try to help you rectify an error if they can. It may not be an issue for them anyway.