Forced to pay for an accommodation without a contract?

Hello!
I am an ERASMUS student who will study in Warsaw this autumn, I find an agency in Warsaw that will help me to find accommodation in this city. After I spoke with the agent and paid to rent a room I found out he is a scammer and will change de apartment where I will live and after my studies will be finished he will not give me back my deposit. I speak with him to send me the contract ( to read the terms) but he didn't make it so I didn't sign anything. When I paid for the room he told me if I will cancel he will not return my money. I cancel my bank money today. The question is, he can do something to me, it is a law or something that it's obligates me to pay him if I didn't sign anything and he didn't sent me any contract?

No - there is nothing legally he can do about it

Is the university providing you housing? The better approach is to use that until you know a Polish person who can guide you through the shark filled waters of Polish landlords (many are great.... a large number.... aren't).