Legally you can ask them not to park there... they may oblige, they may ignore you. If they ignore you, you can complain to the police.... I'm 99% sure they will tell you it's a civil matter & won't do a thing... That has the potential to cause conflict if they (other tenant) continues to ignore you..... OR you could avoid all that & install a security bollard & no need to talk to them at all... They bolt into the ground & usually have a steel shroud that covers the mounting bolts so they can't be moved.... get a fold-able one that will allow access as you need it by removing a padlockjust thinking what could happen, and how I stand legally