Safety in the old quarter (Hanoi)

the old quarter is very deceptive in appearance...go by day and it is full of tourists and people going about their daily chores...but at night it morphs into an underbelly of drugs, muggings and robberies.
Did you know that there are a lot of gangs aka Hanoi mafia and fight clubs mostly led by the Vietnamese youth who are just looking for a fight, the slightest excuse is enough for them to gang up and beat the crap out of you - you being a foreigner is not a deterrent at all..in fact an incentive. Apart form these are the Bulgarian and Norwegian gangs who have a fight club.
the whole point of this discussion???my husband was mugged and robbed in the old quarter. He was badly beaten up and the locals were standing around and watching...at 3:00 am...yes, it is not a great time to be out and all sane people are in bed right? But does that mean that one cannot have a late night in this city? esp in the hub of Hanoi??where one is lured into a false sense of security. The police were of no help and you are better off not going to them in the first place.

And the worst part??? we were told that this is common and one should be very careful in the Hoan kiem district.....by the police!!!