I assumed that would be the case.. the issue I now face is that either they are lying and giving the key to external parties whilst I'm not present - or someone has obtained an illegal copy of it. So I am no longer comfortable leaving the property unattended, and also fear for the safety of my partner if she's here alone and some stranger lets himself in - they have told me I cannot change the lock unless the landlord approves.
So is it my right to change the locks (without their permission) - provided I give them a spare key to the property? Are they wrong to attempt to block me from doing so?
Ok thank you for the information. One last question on this matter..
For the occasions where they have given keys to external parties, with instruction to enter (against my explicit permission) - are they in breach of my tenancy agreement and/or the law? I do have evidence that they have done this.
I'm not looking to attempt to sue them (I'm not interested in money) - I just want to know where I stand on this.