Contact your Department of Neighborhood services. Since you've had communications with your neighbor already, & they didn't result in the desired outcome (ie. dog not coming into your yard) you need to register a complaint with the city.
In my city, complaints are kept annonymous. You can make sure to request that as well. If their dog goes in multiple yards, they won't know that it was YOU who called.
Truly, there are 2 issues at hand here - the first is the dog not being under the control of it's owners, & the second is trespassing/destruction of property by the dog, which the owners are not doing anything to prevent.
If the city is not able to get ideal results (contact them at least 1 additional time if things don't improve) you might want to put up a nice decorative fencing around your permiter - maybe 2-3 feet high. Enough to deter the dog from coming into your yard. (Sucks to be your neighbors if you do this, but hey!)
Good luck, too bad these pet owners are making a bad name for responsbile dog owners. T.
ETA: I do NOT recommend doing something directed at the dog to deter it's actions (noise maker, water spray, etc.) Given that it is not your dog, you don't know how it will react. And prolonged deterance measures can make a dog aggressive/fearful, which can lead to unpredictible behavior. For your safety, & the dog's well-being, any deterrance should really be targeted at the owners, per advice above & from others.