there's only one way - fit gates. We have a similar situation here, in a private block of flats with a driveway and car park at the front, and the committee that runs the place always gets in a strop about vehicles reversing into the driveway and out again, so they're constantly putting plants in pots in the way - but, as you say, they just get mowed down within a few months. So far, they've replaced the pots and plants 8 or 9 times in 4 years - even the heavy concrete pots got broken. As for stopping people parking, they've now introduced permit only parking, paying a company to come round and check and give out fines. They did this because the owners of the flats here refused to pay for gates.

Boulders, b.... great big ones! Or, cheaper than gates, hinged posts that you you can lay down to drive over them.

Hinged, lockable posts. I had exactly the same problem years ago, with people parking on my drive without a thought, and they did the trick very nicely.

If the drive belongs to your landlord you might ask him if he could help - after all if the paving gets damaged he will have to be the one to repair it, which might encourage him to do something.Otherwise if you don't use the drive for parking yourselves I think the boulders are a good idea - nice big ones that are too heavy to shift easily.

To me this sounds like a loosing proposition. Honestly, there not much you can do. I would just move.

Thanks for the ideas everyone.