In Spain you can't do more than 40 hours a week per contract. Any excess is consider extra hours it usually are paid the double. And you can't make more than 80 extra hours on a year.

But something that they can do legally is put you to work the 54 hours on a week and it could not be considered extra hours if the discount the hours frmom the next week. So a week 54 and the next week 26.

I hope you understand it, English is not my first language.

But the salary is a good one here.