Thai is a phoenetic language and the currency can be expressed in English as Baht or Bath. Both sound the same because th can be prounonced as a hard "t". If you have been in Thailand a long time and pay attention to these things then you learn there are many ways.
1. You can't reserve pages. QED 2. You can't tell immigration officers how to do their job. 3. The level of pompous disrespect you show, I would have denied your extension, taken your 1900 baht, and given you 7 days to leave.
only monthy income methods must prove international transfer. All the 400 000 needs is to be in an account in his name only and seasoned for the required time.