Never cancelled but I have postponed. We were planned, packed and had paid for our first trip to Universal but Mom got sick and was put in the hospital, she died a week later. The day were supposed to check in, I had to call and cancel and figured I would lose some money. But, no, they were absolutely wonderful.
They checked our tickets and said if we wanted the price, we had to go within a time frame but that if we needed to wait until after, they would help me figure out how to stay in that price, a cheaper ticket or pay as little of an upcharge as possible. The room type we had booked had no availability for the week we chose, but they gave us an upgrade at no extra cost. And to show how sorry they were for our loss, they gave us a gift card that we used toward express pass! They made us Universal fans for life with that one.