No, I had a minimum of 65,000 TB transferred to my Bangkok Bank Account from my U.S. Bank each month starting 14 months before I arrived there and each month while there for 2 years.
I’ve never used an Agent, I did the application, bank documentation documents, etc., myself. Most Agents are paying off the Immigration Officer and many of them are Immigration Officers.
Your experience is not unusual. Basically, it’s up to the Immigration Agent if you breeze through or have show a return ticket and where you are staying - but it’s very rare. Enjoy I’ll arrive there in 2 more weeks for 90 days for the 27th time.