CANCELLATION REFUND

I made a booking on 25/1/16 and paid the full amount on 26/1/16 where only the 50% balance was payable 7 days from date of booking and the balance 7 days prior to arrival. The cancellation policy states that one loses 75% if you cancel 2 weeks prior to arrival, which I had to do. Seeing that only 50% was payable by that time, I figured I had to be refunded the 50% which wasn't due yet as well as the 25% of the deposit after deducting the cancellation fee. They only refunded me the 50% and refuse to pay the balance to me. I don't understand how they can do it, and will never again make a booking with them. They say they try to help one in changing the dates, but therefore you have to pay an additional fee and I don't see it as trying to help, they only help themselves in that way. I asked her if the people who only pay deposit and then cancel are being held liable for the balance, and she said yes. Where have you ever come upon such reasoning? My sister cancelled as well and wasn't held liable for the balance seeing that she only paid the deposit. I'm not in need of the money, but I feel that they also didn't do anything to deserve it. How many people get cheated the same way???