How can I file a claim against a travel agency that canceled my ticket without telling me?

I bought a round trip ticket with Turkish airlines thru a travel agency and paid for it September 15th with check. The departure time and date on my ticket was October 5th 2013 at 11 pm. When I went to the airport I was told that my rezervation had been canceled without my knowledge and when a new one had been made yesterday for a 1 way ticket for a flight that was today at 12pm. Also I paid 1000 for my ticket but Turkish airlines told me they only received 700. I was told by the airline rep that If I wanted to fly tonight I would have had to pay 900 in fines. The agency never told me about any of this.