DoubleTree by Hilton Sukhumvit Hotel in Bangkok

I expected a professional experience staying at a DoubleTree by Hilton, but this stay was a series of service failures from start to finish.
Check-in Failure: Despite booking 3 rooms with specific requests (King beds, no corner rooms), we were told the hotel had no record of our instructions. One room was even set up as a twin. After a lot of back-and-forth, we weren't able to get into our rooms until 6:00 PM.
Bar "Bait-and-Switch": While waiting for our delayed room, we went to the bar. A brochure at the table clearly stated a 1-for-1 beer promotion, which the staff explicitly confirmed. However, when the bill arrived, we were charged full price. A different staff member claimed the promotion was for a different property, despite the brochure being right in front of us.
Midnight Disturbance: At 12:00 AM, our room’s curtain lights began flickering uncontrollably. We had to have a technician in our room at midnight to stop it. It was incredibly intrusive and disrupted our sleep.
When I brought these cumulative issues to management (Ms. Apple), the response was a "brush-off." They offered 5 drink vouchers (which expired the same night) and a "complimentary upgrade" for a future stay.
As I am not a loyalty member and have no plans to return to this property, a "future promise" holds zero value for the failures of this stay. Management refused to offer any tangible compensation (like a partial refund or credit) for the fact that we lost half a day of our stay and had our rest interrupted at midnight.
If you value your time and sleep, stay elsewhere. There are many hotels in Sukhumvit that understand service recovery better than this property.