Cancel a gym membership in Netherlands

I am an American who's temporarily moved to the Netherlands on business. Back in August I signed up for a 3 month summer special at a gym in Amsterdam, Netherlands. I was under the impression that I was signing up for three months ONLY. I paid in full, up front, and in cash. I did sign a piece of paper but I don't read Dutch. I trusted that the woman would have explained any other terms or conditions.

After the three months expired, I stopped going to the gym. However, they claim that I signed up for a 1 year membership and now owe them money. They have sent me to a debt collection agency who is trying to charge me nearly 2000 euros.

I feel like they have totally taken advantage of my situation. How can they hold me to a contract when I was totally misled? I thought I was signing up for 3 months. I paid for 3 months. End of story. I don't have a Dutch bank account. They only know my name, address, and mobile. Nothing more. Can they really come after me for this money?

What are my rights in this situation? Do you have any recommendations for a lawyer in Amsterdam who could help me with the matter?