It's the plant world's equivalent to Canada Geese - leaves no room for anything else 
Dont ask the council to do something about it they wont know what you mean .
They are the same with ragwort. I have a long-standing argument going on with SMBC about the ragwort they are permitting to flourish on their land all over the borough. They are committing an offence but, unfortunately, the responsibility for enforcing the law on ragwort lies with the local authority..........!
At least ragwort has a natural predator (the slate blue and red cinnabar moth which feeds exclusively on ragwort) which himalayan balsam doesn't (at least not in this in this country).
Unfortunately, it isn't an offence to allow HB on your land although it may be to allow it to spread to adjacent land but from what I've read it seems that the law may only be enforced by your neighbour sueing you when his land is infested