Called asking if I could speak to the manager I was dealing with, she is busy. I'm asking them directly if I am able to change the locks myself, and if they will pay me back.
Waiting for a call back again...
Feels like I am banging my head against a brick wall. Not had any proper response from them yet, or a resolution, or anything.
Well, it's not uncommon for letting agents. Some are very good, but many are not.
At this point, if you haven't already, make notes of exactly who you spoke to on, what, four occasions now, and when. Confirm it in writing. And consider which risk to take, changing locks or doing nothing. It might also be a good idea to get formal legal advice. Do you have any insurance policy with general legal cover, usually as an option? Often, you can get free legal advice on things like this with suitable home or even car insurance.
Sometimes, them finding out that you are acting on legal advice bucks them up. Better is a letter from your solicitor, but that will cost you, and take some time.
Personally, I feel you've been plenty patient with the letting agent, and if unknown persons have free run of your home, simply because they can't be bothered to do their job and check if they or the landlord accessed the property, the risk of waiting outweighs the risk of acting. You have given them reasonable opportunity, and all you asked them was whether any authorised person had accessed the property, and they either can't or won't respond to a simple but urgent query.
Do you have the landlord's contact details? If so, it might be worth a direct approach.
If it was the landlord, or their agent, then you still have an issue with access but it's considerably less urgent than if it is some unknown person, with a key. If it's the latter, locks need changing, and need changing urgently, whether by you or the landlord/agent. If it's the former, you may still want them changed but it's less urgent.
I would give the agent written notice that, because of the risk of not acting, and because they have failed, four times, to return calls when they promised, I would be going to change the locks.
As I mentioned previously, personally, in the same letter I would also formally notify them that they are refused permission to enter the property other than in a real emergency, unless by appointment, and in my presence.
Oh, and fit those cameras.
The downside is that if relations are currently good, getting awkward may sour them, despite the problem being their failure to act promptly. If you're prepared to accept that, and bearing in mind earlier comments, if if it were me, if they won't do it, and right quickly, I would.