I can't really speak to most of your post but I would advise they immediately swap out the lock barrels in the doors and keep a record of all this.
Unfortunately everything is stacked against the tenant here. The hassle they will have to go through to get the property owner and agent to do the right thing is immense.
Maybe they should aim to find another place and not pay the rent for three months.
I suspect the contractors no longer have keys, as the agents were shocked when they found out one had wandered in to the bedroom. I will get confirmation of this before swapping out the locks.
I can't really speak to most of your post but I would advise they immediately swap out the lock barrels in the doors and keep a record of all this.
Unfortunately everything is stacked against the tenant here. The hassle they will have to go through to get the property owner and agent to do the right thing is immense.
Maybe they should aim to find another place and not pay the rent for three months.