The major issue here is your neighbors being far too comfortable with having wildlife living in their house. I love all animals, even the ones that are considered pests. I agree with Diana about moving them but the problem I see is once the raccoons are out of the scene, there is a high chance that either more will move in or something else will. Your neighbor would have to block all access points to make sure that nothing else can move in.
Are you friendly enough with your neighbor to approach them with this situation? I don't really think you should even have to do that, but sometimes people need a mental goose.
I'm in the US so I don't know what kind of critter control options you have in terms of protecting your garden. Here we have powders that can be put down to motion detectors that use a 9 volt battery with a couple cups of water that spray the animals. I was poking around yesterday looking at the motion detector option as my neighbors cat likes to use our gardens as a litter box.
The only other thing I can think of which again shouldn't even be your issue is to make sure that there is nothing around to draw them in. If there is any kind of food around that will bring them in. I feed the wild birds, chipmunks, squirrels, wild rabbits, ect... in our back yard and every so often we have a raccoon that comes in to graze. This happens mostly during the winter, but they like suet as it is high in fat. If they are hungry enough, they will eat seed but they prefer suet. They're also smart and can pop the lids to our trash cans, so using something like a bungee cord keeps them out of the trash. If for whatever reason they decide to chew through the bungee cords they are going to get smacked in the face which they won't like.
I lied, I do have one more thing. If you have any type of wildlife rescue places around, you could also try giving them a call. They may relocate them, but again, if the neighbor does nothing to actually fix the problem there will probably be a similar situation at some point.