Lights and power going out during 1AM-5AM, whilst not ideal, is not the end of the world. But what actually happened sounds like an unmitigated disaster for a supposed luxury hotel (and I'm far from one to rush to hyperbole), and I would be disputing the credit charge for the simple fact that you were deprived of the purpose of staying in a hotel (i.e. sleep) unless the hotel is forthcoming with a more suitable compensation very soon.
The very aghast and apologetic GM at Four Seasons Dubai invited my boss back for a complimentary night's stay with barely a word when he had a fire alarm during the night, which sounds much preferable to what happened at GH BKK. Personally, I would have returned the banana chip addressed to the GM making my displeasure amply clear.