At the risk of digressing,
(Disclaimer: I am British Born Ethnic Chinese).
You have to realise that a LOT of HK. Chinese people can only process a bite of information at once, a certain department (and even our line managers) on whom which my colleagues and I greatly depend and contact almost daily need all of our information in chunks (Chinese/ English) and I don't work for a bank. You can't explain things the same way you would to any other person in your home countries. Even if you think that what you are saying to them is perfectly pared down to the bare bone essentials, there is every chance that even in Cantonese it's overloading them with information. This particular department is very surly and rude about the fact that they are essentially simpletons.
Please contrast the following examples:
Most people:
" I have guests here at XYZ. Hotel who would like to join our AM. ABC. tour tomorrow please, 2 adults 1 child, can you please tell me when they will return to this hotel tomorrow night."
Department in question: (requires chunking)
"I am calling from XYZ. Hotel."
"I have three guests."
"2 adults 1 child"
"The child is XXX years old."
"They wish to join the ABC tour tomorrow."
"It's the morning ABC. tour"
"Can you please tell me what time they will return to the hotel tomorrow?"
"They don't want to get back too late."
Cue surly and rude questions about my ability to remember the return times for over 7 different hotels.
Cue phone being slammed down.