@Janin *****
It's like this. Once you cancel, the last day you can stay is what it says on your termination letter. This is typically a few days or in some cases up to 2 weeks later. Usually you and the HR department agree on a date and often it's the last day of the month, even if you're terminated earlier in the month.
You can stay up to an extra 7 days beyond that date, if you pay another 1900 Baht.