K. Sirinya, 
Please read through the contract one more time as I believe that the hotel has right to process the full amount for entire of stay for this non-arrival booking as it says "In the event of no show from FIT, a no show charge will be applied for duration of stay or as negotiated in writing with hotel"
Along with this email, I have attached what we have sent to GTA initially and it was acknowledged by GTA itself on no show charge will be based on contract. 
If the first argument is being disputed, please refer to the other attachment on cancellation req by GTA which was sent on 2nd Jan. With this assumption, believe that it will be fallen back to our festive policy. 
Trust that this will help you to figure it out!
Thanks
Fez