House Rent Contact - Complications

I have rented Flat in Jan, 2014 and signed Contract of 1 year and paid 6 months rent, after 6 months (1st july 2014) i talked to property office that i want to leave this flat, he agreed and i gave him keys.
Today i received called from Property office Owner and he told me that the Flat owner ask for 6 months Rent as per contract it must be one full year.

I replied strictly that its not my problem. He told me that Flat owner wants to go in court against me.

What are the legal ways to handle this issue?

Thanks