What are the requirements for renewing a Thai wife visa, and is there reliable information available?

Dear All

I am currently living and working in Thailand. I have a Thai Wife visa. However, getting reliable information on how to renew the visa is a challenge. Thai Immigration does not answer phones or respond to e-mails and I cannot find a single clear list of requirements via their websites. I am told that I need THB 400,000 in the bank X months prior to applying. However, I am also told that having an income of THB 50,000/month means I do not need THB 400,000 in the bank for X months at all.

Basically, are the requirements separate but equal? Are there any considerations of which I need to be aware if choosing the THB 50,000/month? If choosing the 400,000, what is the number of months?

Is there a comprehensive, up to date government list in English available online and, if so, could you please provide a link?

Thank you. My feeling is that one is forced to go through Thai lawyers, who charge steep fees to do that which anyone ought to be able to do were the information made readily available.