@Vasco4
Sorry to hear about your situation. From your reviews, I can see that you are a helpful host and try to keep your guests happy. I agree with @Normen0 's approach as it seems these guests are not allowing you a solution.
However, I also had a look at your ratings and reviews and 4.5 is low, especially for such a nice apartment. When looking at the category ratings, it seems that the areas where you are getting rated down are location and value and that guests are maybe then rating you down overall on these factors, as all the category ratings are higher than the overall rating.
It doesn't really seem fair, especially as there is nothing you can do about the location except that you make it crystal clear so that guests are not surprised by the distance to the centre, lack of parking or whatever. I am sure you probably already try to do this, but I find that you really need to SPELL it out for certain guests or they just ignore the information. I would ask them when booking to confirm they have read the location section of the listing and understand the distances etc.
As for value, well I haven't checked your prices but I feel like it may be something you can easily do something about. There are trickier things, e.g. a few guests mention thin walls/noise from neighbours. Again, not much you can do about this other than make it clear to guests in advance (and do inform them if there is construction going on nearby).
So, where I would concentrate is on the things that can affect a guest's perception of value that are easier to improve:
- No heater in one of the rooms
- Worn out or uncomfortable mattresses (if you can't afford to replace the mattresses, maybe look into buying thick mattress toppers. That's what I have done and my guests love the beds now)
- No wardrobe space to hang clothes
- Lack of basics like hand soap, shampoo, dish soap etc. One guest also mentioned things like salt, pepper etc.
Now, you may have already improved some of these things and I see that several are listed as amenities, but your current guest is now freaking out about lack of towels, toilet paper and hand soap. If that's all the guest is complaining about, it seems their reaction is a bit over the top and they are going to be a lot of trouble in other ways, but going forward, do make sure you provide plenty of these basics as it seems to be a recurring complaint from your guests. It doesn't need to cost much and could make a real difference to your reviews and ratings.
These things may seem really small, but I've had guests who tell me about other Airbnbs they stayed at and didn't like purely because there was not enough toilet paper (they felt resentful that they had to buy some themselves for a short stay) or lack of towels, so these things really do matter to guests.
Anyway, I hope you get your current situation resolved. I would definitely follow @Normen0 's advice here.