Get a tap lock and lock the water tap and cut off the electricity.

Secondly inform them to move out since there’s outstanding.

No point for u to shout at security. They are paid to do what they do and only take orders from their boss. Pls don’t say u paid their wages lol

But u can make a scene at the management and default on management so they will block all access. That’s some shitty management u have to be honest. Or maybe they just don’t want to be involved in any tenancy disputes. But again they should be able to take ur order as the owner. Block all access to the unit.