Can I extend my Non B visa for 7 days to obtain a work permit in Thailand?

When you apply and get the Not approved stamp and the 7 days to leave the country, you have to leave the country. During these 7 days there is NO option for appeals or applications for new Extensions.

If you apply extension without all necessary documents, it would be denied, and you COULD be granted 7 days... this 7 days means to leave country because extension application is denied. And if you can apply and be accepted new extension in this 7days period is up to your local immigration. Some would let you, some wouldn’t accept application.

Non B visa of 90 days CANNOT be extended to 7 days.