You could think of it as a great opportunity to...

1) Get better acquainted with your neighbor and both of you address the
issue together

2) Eat bamboo shoots every spring and summer... every shoot that begins to
break ground as soon as possible dig down to where it connects to the
rhizome and cut it off. Boil it up and add some sesame oil (my favorite) Umm
Umm good

3) Start your own bamboo forest... but put in a 24" deep solid 60 mil
plastic rhizome barrier where you want it to stop!!!

Good luck,

Djubaya