It depends on what you are talking about... The fee you mention is the regular reservation fee or is it something else?
You get charged a reservation fee for every reservation (about 3%). But if they charged more than that, then it could be a cancellation fee for your last cancellation.
How did you cancel the reservation? If you simply pressed the button to cancel the reservation, than that is probably it. If your father was sick you should have called them, explained the situation and had them cancel the reservation for you, that way you wouldn't get a fine.