my drain is blocked ( the one where the waste water goes )?
Answers:
If it's not the sink then what is it? If the plunger doesn't work, nor unscrewing the swan-neck piping, then you might want to consider using some chemicals specially designed for clock ups.
By the way, which hotel in Hong kong did you stay at?
Other answers:
get your plunger.
get your plunger.
stick your hand in
The problem is most likely occuring in the trap. The trap is the "U" shaped piping underneath your sink. There is probably some debris that is clogging this area up. Grab a plunger and try to push the debris out through the trap area. Remember to push and not pull. Pulling will cause all the nasties to come back out onto your sink. Ewww.. =]
TRY USING CAUSTIC SODA AS YOU DID WITH THE BLEACH. BE CAREFUL THOUGH CAUSTIC SODA CAN BURN THE SKIN. GIVE IT AMPLE TIME TO WORK.
FAILING THAT LOOK UP "DRAIN DOCTOR" IN YELLOW PAGES.