Letting agents sent contractors to my home when I wasn’t present despite texts stating I didn’t consent to this. What are my rights? England

Hi, please forgive the throwaway. I know this isn’t a huge deal and likely sounds dramatic but it’s a big deal to me and I’m not feeling great.

I rent from a letting agency. A few days ago I get a text from a contractor saying they’re booked in for my annual gas inspection, all fine, except the day (today) they were booked for was one when I wasn’t home. I told them this and proposed an alternative date, telling them that I am uncomfortable not being present while they’re in my house. Letting agency texts me that they will give the contractors a key - I text the letting agency that I am not comfortable with this, and send the same text to the contractors. There’s some back and forth about them being on holiday next week but the last text was me telling them, again, that I am not consenting to them coming that day while I’m not present. I realise I should’ve pushed to confirm a date sooner but as I didn’t hear back, I assumed what I’d said was okay and we could reschedule when their holiday was over.

There were no texts or calls today.

I came home from therapy about 20 minutes ago and my things have been moved around and someone has clearly been in my house. I’m a vulnerable person, specifically young woman, who lives alone. I’m disabled - I have schizophrenia and PTSD that stems from someone who forced their way into my house and who is still actively stalking me. This is the reason I always endeavour to be present for anyone needing access to my flat, because those events were recent and I am still not okay - my letting agency were aware and always communicated with me brilliantly, but they were bought out a few months ago and the new staff are not so great. There are outstanding repairs, texts and emails appear to have disappeared before but this instance is having a major impact on my health. I’m triggered and I’m spiralling.

I’m not looking to sue or anything like that but I do want to complain to my agency, but I’m not sure if I’m able to over this? I’m not a problematic tenant, always paid rent on time, never caused any damage or problems, my house can get messy if I have an episode but that’s it. In fact I’m recovering from one right now and I feel so incredibly violated that I’m scared it’s about to massively set me back. There’s logically no reason for me to be evicted but I’m scared of being kicked out if I complain, so I guess I’m asking if I’m “allowed” to or if this is just something I need to get over? Is there anything I can cite in my complaint?