Deposits policy for holiday accommodation in Spain

I am in the process of booking an apartment somewhere in Spain and I've been told that I need to pay 30% of the total booking amount in advance to confirm the booking (fair enough) and after that I need to pay the remaining 70%, 15 days prior to arrival.

Having travelled in various countries across Europe, no one has asked for paying the full amount before I even reach the place.

My questions are:

1. Could they enforce this kind of payment in advance?
2. Is there something official from the ministry of tourism in Spain that regulates deposits that I could refer to?

Of course, any thoughts along these lines are more than welcome.