Hi Peter,
I saw you asked your questions several times and it does not seem to be a question you would discuss on Twitter or by phone.
It's a legal matter.
What I would do: Send the tenant a Cease and Desist request by registered letter.
Copy that letter and a proof that the house is yours, maybe the rental agreement or the deed.
Then send another registered letter to airbnb Spain, add the copies and tell them to remove the listing on the spot as you will hold them accountable for damages and lawsuits from local authorities.
You should find the office address on the yellow pages or in the impressum of the Spanish webssite.
This forum is not moderated nor read by airbnb staff. It's a Host forum, moderated by an external service provider. Their job is to clear out abuse and swear words and to animate the forum. They are not lawyers.
Good luck to you!