Posted: 09/06/2015 at 15:10
Just a small point: if it comes from next door it is not your plant, neither are the grapes!!
If your neighbour decides to prune it on his side you can do nothing about it. He may be getting poor growth/fruit on his side!! He may get rid of it. Have a friendly chat with him!
You definitely will need to take out some of the bunches and ultimately grapes within each bunch.