Thai law does not have a legal problem for resign of staff, for employers and employees agreed. I’m suggestion “Khun Alex write a letter of resign from today.
The rules of Hansar Hotel “All staff to resign before 1 month in advance, otherwise, will not be service charged”.
About expenses incurred will be recovered from Khun Alex, HR not has information about all expenses of Khun Alex, HR know “Expiration date of Work permit November 17, 2015.