Your frustration is understandable. I had a similar issue back in July last year when settlements were in their infant stages; Soft Claiming & Plot Reservation
That said, until they outright enclose your settlement, there really isn’t anything you can do. You don’t own those plots until you own them. If you plan to expand in the future; plot it.
My only advise for now is to ignore it. 500 plots is a heavy commitment, so if they really are just trying to grief you (which is too early to say) they’re really going out of their way to do so.
Carry on as you would and perhaps you’ll outlive their beacon.