Have you Googled the company name, directors name etc?
Anyway here is my advice.
I keep telling myself I will one day write my own new verison of the book “The Emporer’s new clothes”. I can tell you the chapters are already filling up!
There are millions and millions of properties in Spain that no-one wants with desperate owners praying for a buyer to come along!
So what on earth is the purpose behind a reservation fee or deposit in the current climate. I think people just do things a certain way because that’s how it’s normally done, and never question the purpose behind it.
I would pay the full cost of the property at completion and if the auctioneer insists on a fee before completion I would look elsewhere.
The other issue is that whatever you are paying today, In 2 years time you could purchase for considerably less, from either (or both, but certainly the first)
Spanish property prices falling a further 20%
Spain reverting to the Pesta, or some form of devalued Euro when Germany pulls out.