I am talking more as an ex-pat where despite having every detail on the Central Data system, I am required to provide the same data three times a year much of which has not varied in TWO DECADES! Different offices in different cities will ask for different data and/or permit different things.
See answer above. I've stayed 20+ years in Thailand; it has cost me 50% of my State Pension. I've earned the right to complain after spending millions of baht here. I've never used an agent, you're obviously uncaring about finances. I've got Visas for friends/wives/girlfriends/ for UK; USA; EU so I can find my way through Thailand's deliberately over-complicated procedures.