Scam with flat renting agencies - help! (Barcelona)

Hi, I look for help for more advised and more experienced people than me! I moved in Barcelona last year, full of trust. I rented a room in a flat via an agency, and did all correct (gave a security deposit and paid all my rents).
Now it has been 7 months I left this flat, the agency doesn't want to give me back the deposit... they are now lying to make it as if my deposit is due, because of broken things!
What can I do? I called on some lawyers, but they are willing to charge me before even knowing if I can get back any money... Is there somebody with experience on that? With contacts for consommation associations?
Thank you very much !!!