try all the banks but try Bangkok Bank first in each of the venues. From experience they are the best bank for dealing with immigration issues. Because you have a long term property it should be possible. If you can get a list of requirements post them and I am sure people will be happy to help you meet the requirements. This is Thailand there is always a solution. 😊🇹ðŸ‡
I understand exactly what you are asking. The only solution is to get the original text in Thai and get a competent translator to answer your question.
If you need a competent Thai-English translator message me directly.
the website is a bit misleading. It does indeed say 3 days processing but in the Q and A section it clarifies that if you apply on a Monday your visa will be available on Wednesday.
I have been luck enough to live in Cha Am for 8 years now. In that time have interacted with many Government departments. Up to how it has been a pleasure to deal with them all.
you can try to justify the finances however you want. You do not have a legal visa/extension. If you are ever challenged on meeting the financial requirements of the visa stamped in your passport you won't be able to do it.
I am no lawyer but my understanding of the immigration Act is that is you no longer qualify for a visa you are on overstay.
Using any agency to circumvent the law carries risks. I am not prepared to accept those risks in my life.