I did mine in Chonburi (Jomtien/Pattaya), yup they wanted that insurance, the TM6 card(seems like everyone wants this),proof of paid residence, the required fee in cash, your actual passport, that silly ASQ form you got upon testing in ASQ hotel, a photo, passport biometric & visa page photostat copy, completed TM7 form, STM2 form completed. They rifled thru these docs I presented for over 15 mins and voila, an extension stamp was inserted into my passport.
I have no idea if any of this was overkill, but it did the trick. Go figure, this becomes the required 90 day check in, so there is nothing else until the next visa renewal.