I live near the Cambodian border and this is exactly what my bank was like just before they closed the border. Large A4 file folders all over the office floor, but at least there seemed to be some semblance of order to the system. I can imagine branches with a lot of foreign customers are similar right now
You don't provide your nationality but if your embassy in Thailand provides income certificates you can use that but an increasing number do not. If they don't you can transfer a minimum of 65k baht into your thai bank from overseas each and every month for a full 12 months prior to applying for your following extension. You need the full 12 months as a minimum so if you are currently part way through an extension start now so you are sure to meet the criteria, the 65k baht can be spent once it shows in your bank account