what to do

we got home to fait acompli ( hope that is spelt right) upset the next door neighbour who is 92 as they have intruded on her garden and put junk on her garden - not very nice people. we have someone coming to measure the boundaries properly. I hope we are right and they are wrong because they have been so horrid and rude even if they are right there is no need to behave the way they have, I have decided not to bother talking to them until we know the boundary and then we can sort it.