Sorry to hear of your problems at this Hyatt. I have stayed many times at the Hyatt Lowndes, around the corner from the Carlton (where I have also stayed). I prefer the Lowndes, as it is smaller and more personable, but you can still use and charge to your room the restaurants at the Carlton. Patrick, the concierge at the Lowndes, is truly a professional.
I agree each chain has a problem property (or more). I have personally blacklisted the Hyatt in Cologne and will never stay there again.
Better luck next time.
Cheers.
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Have passport, will travel...
LAX, LHR, et.al.