What should I do if my visa extension paperwork is incomplete before it expires?

When I was working in Bangkok my colleague had an issue with his Non B. It was about to expire (as in less than a week) and no one was aware. They were under the false assumption it was a one year visa. No one understood it had to be extended before the 90 day mark.

The company hired an agency as they were clueless. The agency gathered paperwork and headed to CW to file for the extension. There were errors and other paperwork was needed from the company. They gave an extension for the company to gather the paperwork required. I believe it was for 14 days.

Generally, no. There's no temporary extension to finish getting things together. That's why you can apply for extension 30 days ahead of time, and even 45 days at some offices.

You might be able to apply for a Covid extension currently, but you'd have to find out if that will impact your ability to extend your non-B (my assumption as a work extension since you said employer).

But you cannot work on a covid extension.

You have 30 days before it expires to renew. Planning ahead is the best solution.

Unfortunately the usual answer would be no. You may find a lenient officer who will cut you some slack, but probably not. You may be able to get a Covid extension which would give you a further 60 days. Else you may need to pop over to another country and re enter to get more time.