My neighbor's bamboo has grown nearly two-stories tall and is blocking the light in my living room and now a bedroom. About two months ago they cut down the tops to ~8 feet but now it's grown back even faster & thicker (branching instead of long shafts).

What can I advise them to do?

What rights do I have to stop their bamboo from turning my townhouse as dark as a basement??

Thanks for any suggestions!!