Can I get $$ back?

In September, I was to go on a trip, but do to circumstances had to postpone the trip. I called CheapoAir twice before deciding what to do. I was told that my options were: 1) Find tickets at a later date and would be charged $200 per ticket OR 2) Get a refund for the tickets, but be charged a cancelation fee of $150 per ticket.
Because I could not get a ticket for the date I wanted (to far in advance for cheapoair to reserve), I chose to get a refund. I should have lost $450 (3 tickets) out of the $1640.99, receiving 1190.99. I have received a total of $534.60 (meaning they should owe me $656.39).
I am still owed over $600 and have spoken with cheapoair at least 8 times on the matter. Most of the individuals I have spoken to could not help me and told me they could not get help from a supervisor. I am told that customers can not talk to the refund department directly, after they have dealt with a case (hmm...now I know why!). Finally today I was told that the airline company they (cheapoair) buys tickets from also charges a fee for cancelation, which was $400. I was NEVER told this when dealing with Cheapoair in September when canceling my flight. I again asked to speak with the refund department, as this is who I dealt with before and they never told me about the airline fee. The woman I spoke with, basically said that she can not do anything about the misunderstanding except to explain it to me now. I stated, "So after the fact, you clearly explain this to me? I should have been given the facts in September"
I am feeling quite frustrated at this point and wondering if there is anything I can do.
What can I do legally? Can I take action, or am I just screwed?
Can I take them to small claims court?