Is this contract void and what action should I take?

I eneterd into a gym membership with the terms of 150.00 down which will be reimbursed to me by my health insurance as long as i am a Gym member for 4 consecutive months and 21.49 a month . I was a member from Oct 2008 to march 2009.(6 months). I obtained the paperwork from the gym to file for the refund and was denied by the health ins.due to the 4 consecutive months not being in the same calender year . I was never informed of this qualification by the gym which sold me the membership and I even ask for clarification .