Landing without permission (unless in an emergency) is blatantly rude in the flying world and if it happens, and you aren't happy about it, you have every right to be annoyed.
Only if your field is marked private. It
my right to land in any public field.
To be perfectly honest, if someone lands without being invited, the landowner CAN, if he wishes to stop aircraft landing, charge what he likes
Do you do the same with all tresspassers accidentally walking or driving across your land? I hate to be held to ransom by someone like you.