Guest arriving one they earlier than their reservation

[Ynse-Yke0]

It just happened to night guests arrived at Friday night 2AM, who had reserved for Saturday night, asking the permission to arrive between 12PM and 1AM. On which I agreed. They  sustained that they were comunicating to me that they would arrive on Friday night, which was for them Saturday night. Their request: "However our flight does not land until 12pm on the 9th of October and we were hoping to check in our bags that night at around 1am/12,30pm! We would be extremely grateful if you could help us put on that front! Grazie, " and reservation starting on Saturday. When they arrived I made clear to them that they were lucking I could help them out, as I had no reservation for that night. As they only contact when they were already on their way to the apartment, all preparations had to be done under great pressure, and only after realized myself that I checked them in without a mask. Which I normally would have taken care of. I made clear to them that they were lucky as I had no other reservation for that night and that it would be the case to pay one night more. They did not understand, insisting that our agreement was for an arrival on Friday night. What should I do? 

[Branka-and-Silvia0]

@Kathy842  yes we use 24 h sheme or “noon “ “midnight” words, it is easier to understand

[Ynse-Yke0]

@Kathy842 
Thank you for your comment. My answer is a bit late as I needed som for reflection. After having had this experience I did some research myself and must admit that I never knew that 12PM starts from noon till just before midnight. The only excuse I have is that English is not my native language, while my guests were, although being Irish, English speaking. Their exact message was "However our flight does not land until 12pm on the 9th of October and we were hoping to check in our bags that night at around 1am/12,30pm!" Their reservation started in fact on Saturday from 15.00PM. They certainly were comunicating to me that they were going to check in after midnight and not Saturday-afternoon. So they certainly inforced my idea of 12PM being at midnight. Now I know better.
Because I convinced myself that their error was not intentional, but just a result of bad comunication, I did not ask airbnb to take measures and make them pay for the extra night.
However I don't think they understood I did them a favour, as their appraisal of the apartment was quite low, in line with their quite unfriendly attitude. I probably should have refused to check them in.

[Ana7]

@Ynse-Yke0  I am completely sure that these guests know what they are doing, and that is taking advantage of your kindness and confusedness.

[Ynse-Yke0]

@Ana7 
I left the possibility of doubt open, but I have some doubts about that.