Yes, I know. Was denied myself with a Non O and residence certificate in Isaan. (Asked for a housebook or work permit as well). Also denied in 2 branches in Chonburi without extension of stay(they asked for minimum one year "visa"). Allowed in one in Jomtien without any issues.
Almost impossible without a Non O visa, and even then you might meet some difficulties. Some branches also demand a housebook or that you’ve done your first year extension of stay to get an account, but you will succeed with a Non O if you visit several branches.
Yes, just get your TM.30 updated through your hotel and landlord and visit your immigration. Most immigrations accept extension 30 days prior to expiration date, Jomtien and Samui within the last week.
Foreign lady married to Thai man is excused for any financial requirements. A foreign man has to prove 400K baht for the first year and can switch to the income method for the second if he earns min 40K baht a month inside Thailand. If your embassy offers to give you a affidavit letter regarding income some immigrations also accept monthly income/pensjon from abroad.