Changing Locks on Rented Property Question

RHemmings

Summary:

Changing the locks: He likes the idea of swapping locks when the EAs, tradespeople, or others come around. As well as my impression that he wanted to take control, he does feel disrespected by the EA and feels that this strategy would be sort of like putting one over on them. In fact, he said that he enjoys the thought of that. 

Spare Keys/Chain/Alarms. He doesn't want the EA, Landlord (who has never visited or communicated directly), or tradespeople entering without agreement and without him being present. However, all members of his family (parents+siblings) have keys to the flat, and would have both sets of keys. It seems to be good relationships and trust all round the family. When they visit they will knock, but it has been agreed that if they want to check up on him if he doesn't answer, they are welcome to open the door, enter, and check the situation out. So, he doesn't want to make it more difficult for family members to visit. Which a chain may do. I'm not a mental health professional and don't understand properly, but he mentioned being in bed and not being able to get up or respond. Clearly he could have an alarm and share the pin code with family members, and the idea is now floated. But, in the meantime, he is happy with the changed locks. He doesn't want anything resembling identifying information posted, but he has siblings living in two nearby towns both within an hour's drive. If he locks himself out, they can help. This hasn't happened yet. 

Asking the EAs to knock and not enter with the key without knocking: Last time we refused the EAs entry on their unilaterally decided date and offered them a number of choices (in the same email), and they chose one and followed that. He requested that in the future they negotiate a date rather than just unilaterally decide one and inform him. The next time this negotiation happens, he will politely ask them to knock when they arrive and not enter with the key. 

Wearing out the lock: We removed locks to measure them. (I know you can measure without removing them but we only had a flat ruler. It was my suggestion to remove them.) They come out and go back in easy. It's a metal bolt that screws into a hole in the metal body of the lock. The metal bolt tightens against the metal plate in the door. I may have the names wrong, but it's all metal. Neither of us are good at DIY, but it looks to us as if the locks could be changed tens if not hundreds of times without significant wear provided that care is taken not to strip the thread. It seems like the plastic of the door that is morely likely to be damaged, and care will be taken concerning that. It should only be a few times per year. Approximately.

I think that's most of everything. Thanks to everyone who made suggestions. They are appreciated by both of us. I apologise if I missed something in the summary.