Just got my annual non-im O A retirement renewal today (including multiple re-entry). I had done my homework and had all my paperwork in order and it took less than 30 minutes. The staff were nice, polite, and efficient.
Actually, I've had 5 annual visas now, the original at a Thai Embassy in the U.S., the first renewal at Soi Suan Phlu main immigration office in Bangkok, second renewal in Hua Hin when they were in the Police station and two renewals at the current Hua Hin office and I've never had a problem.
I always research on this forum and stop by the office a week ahead to see what, if any, requirements have changed, then go in dressed neatly and treat the officers with respect and it is always returned.
I renewed using annual pension income and here's all I needed:
For the Retirement renewal
1) TM7 form filled out
2) 1 copy of my passport - photo page, every stamped page, and the attached immigration departure card.
3) 1 4x6 photo
4) Certificate letter from the U.S. Embassy stating the amount of my monthly pension.
5) A copy of my Yellow Book (house registration)
6) A hand drawn map of where my house is
7) 1,900 Baht fee
For the Multiple Re-Entry stamp
1) TM8 form filled out
2) 1 copy of my passport - photo page, every stamped page, and the attached immigration departure card.
3) 1 4x6 photo
4) 3,800 Baht fee
Other than that I had to produce the original of my passport and house registration for verification and that was it! Easy as drinkin' a cold Heineken on a hot Thai afternoon.
under oath that I make a million dollars a month pension and they will give me an officially stamped letter saying it is true! 
) that much and I tell the truth and take proof, but they've never wanted to see the proof. 
