Berens Estate Management - Non - refund of deposit

I claim for the immediate refund of the security deposit I left for renting one of the rooms in the apartment of Av Defensores Chaves.
The contract establishes an immediate refund of the money after the check-out, and the emails they send establish a period of 90 days. Unfortunately, 113 days has passed and they still haven’t returned the money. They always give excuses like “we are not in the office”, or “we will go to the office next week and solve your case”. After postponing me all these time, he just answered (the manager, Filipe Berens) that they don’t have an office.
Therefore, this looks like a ghost business that steals the security deposits from their clients giving excuses all the time for not refunding. They also don’t answer phones, neither emails.
One of my flatmates is having exactly the same problem, and as I’m reading here in all the complains, they do this to everyone.