While we always try and it's good to differentiate between an extension and a visa. Immigration officers do not use the word extension. They use the word visa
I went to the immigration office after cancelling my work permit, the officer looked at my visa and said" you still have a valid visa, go and process a new work permit and comeback for a new extension " those were his words. It took me 10 days to get a new extension. And they did not cancel the old extension they issued a new extension.
If your wife is in bangkok, to cancel her WP she must go with a colleague from her previous school to cancel the WP. I did mine yesterday, and applied for a new one today.
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