1. You're a social media manager (according to your Facebook profile), and using this attitude to me.
2. You are talking to someone who's an expert about visas and extension of stays who have helped thousands of people staying in Thailand legally and safely.
3. You believe what I'm saying is incorrect even AFTER I give you the evidence?
The Thai Immigration office is overseen by the Royal Thai Police. The laws that direct the immigration officers on what is required to issue extension of stays are called "Police Orders" 😮
A person can study any subject on any visa. I recommend getting a single entry tourist visa, and extending it once by 30 days. It will give you a 90 day stay.
And why didn't you disagree with the immigration officer on their decision?
Sadly, you can not pick and choose your immigration office. If there are multiple immigration offices in Trat that can help you, then you can any immigration office.