Neighbour rents their place on Airbnb - help!

I live in a standard 2 floor Victorian terrace in zone 2. We live upstairs and our neighbours have the ground floor. For a while downstairs have tried to sell, but moved out and put the property on Airbnb for the time being.

We have had a couple of issues since then - they removed their doorbell so takeaways go to our flat, Airbnb guests have struggled to get in as our shared front door has a knack etc.

But today the weirdest thing happened. Some new guests knocked on our door and asked to use our WiFi because there wasn’t any in the Airbnb.

At first I said no because they needed to take it up with their hosts. They then said that because they had no internet access so they can’t contact them. (They have foreign accents so I assumed they are travelling).

I begrudgingly let them use our WiFi but am now thinking what I should do as a next step. I’m fed up being an unpaid concierge for downstairs’ Airbnb. We don’t have downstairs’ numbers so any suggestions that don’t require direct contact with them would be really welcome!

I use Airbnb when I travel abroad myself but I do think it’s unfair that me and my partner are being inconvenienced like this. I feel a bit weird about giving my WiFi out as I don’t know these people but they seemed desperate and offered to get me a bottle of wine for the inconvenience. They have a kid too which made me take pity on them.

UPDATE: Thanks for everyone’s response. I raised the issue with the host and Airbnb after finding the listing. Waiting for a reply! I’ve posted my complaint in comments.

Update 2: I’ve also changed the password for the WiFi. Definitely scared me guys!