I have had to show that I had 800,000 baht in my bank account 3 months after receiving my retirement extension. I have had to do this for the last 4 years. I go to PathumThani Immigration office
I had considered using them a few years ago but decided not to since their price was way to high plus when they said I did not need any back up documentation just my passport, I thought then that there was something not right. Glad I did not use them