What are the options for extending my Non-OA visa in Thailand without leaving the country?

A user is seeking advice on how to extend their Non-OA visa in Thailand without having to leave the country. They are a US passport holder with a Non-OA entry stamp valid until February 21, 2021, and have maintained the required 800,000+ baht in a Thai bank account since mid-December 2020, along with having the necessary insurance. There's concern about the tight timeline, as they have only five days until the visa's expiration and are told that it takes a minimum of two months to apply for an extension. The comments suggest that if all paperwork is in order, the extension process is typically swift and can be completed in one day. It is advised to gather all required documents ahead of time to avoid issues during the process.