Neighbour parking outside our property in a non parking area damaging the ground

Our neighbour has been parking on a grass verge outside our property for roughly a year. Wooden bollards that should stop this have been removed and another one now damaged to make it easier to come and go. The bollard is shown as standing(nearest our driveway entrance) in the photo but it's is balancing in that position as its been broken off as shown in another photo. So they came come and go as they please. I have advised them not to park there due to the damage to the ground especially when ground is wet as you can see the trenches the driving on has caused. This did cease for a month or so but has now been going on again ever since. Can the posts / bollards be replaced to prevent cars parking there.