Ok, so today I went do Labour Office first and cancelled my WP - it took less than 10 minutes! Then I went to the immigration to ask about my Visa status and to make sure if I need to cancel or do anything with the extension of my old visa or not - the officer said that everything is fine and there is no need to cancel it.. He said that I can apply for new WP and new visa.. So i guess it depends on the officer and his knowledge about visas...
I mean that my 1-year non-b visa (from the previous school, which I was pretty sure was already cancelled, stamp looks similar like the one you posted) says I can stay in Thailand till 19th October. But this month I didn another visa run to get a new Non-B visa, which is valid till 29th October
seems to be totally complicated... the last one is a stamp with my new Non-b visa which i got when I left Malaysia, saying that its valid till 29th October. My old 1 year visa would be valid till 19th October.
Thank you. I know about cancelling visa, when I left my previous school I left the country immediately to cancel my visa as I was afraid of having an overstay. Now I have a new Non-B provided by new school.