Better to just speak English with the immigration unless one is really fluent in Thai .
I always used to laugh in pattaya when some guy speaks some bar girl Tinglish with immigration. I understand that English isn’t everyone’s native language but no need to talk like you’re at a beer bar while at immigration.
I just speak English, wear a three piece suit and carry a leather briefcase.
that’s what this service is. As you said you can’t fly on it. It’s fraud and hopefully they crack down on you people attempting scams against the Kingdom of Thailand