It seems very hard to stay on topic and above all, one person just comment it is not true but fails big time to tell what is according to him the truth.
This page is called ADVICE, if you know better show how it should be, but be aware stay on topic, other cities, other extensions, other visa or even another country has no added value to a question and only gives reading a headache and nobody understand what we are talking about.
If you have a question, don't be shy and start your own topic, you will get to the point answers.
Thanks for all the contributions and I hope the OP still understand that the best option is to visit the Immigration office to get the hand out with requirements.
The 8000.000 Thb needs to be in the Thai bank account on your name at least 2 months prior applicalion date until 3 months after and the rest of the year not less than 400.000 thb.
You need copies of your passport, copy tm6 departure card, copy address registration, letter from bank, updated bank book, passport picture, drawing of your address location and fee 1,900 Thb.
Best is to visit the Immigration Office and ask the list with hand outs, I might have missed one.