I have renewed my retirement visa myself for the past 19 years. Never a problem !! Previously it took about an hour, but now with the online appointment system, it takes less than 30 minutes. Fill in the application, attach your photo, update your bank book and obtain the bank verification letter the day before, attach all the required documentation copies and pay the fee . Once you get your passport back, get your re-entry stamp (last few years less than 15 minutes of time) and you are done. Since you can now do 90 reporting online, no need to see immigration until next year. Why pay an agent 7,500 + Baht ? I would rather spend the money on a nice getaway weekend with the girlfriend !!