Sorry, but the cancellation penalties are the norm. Most hotels will charge you at least one-night stay in cancelling the cheaper pre-paid rates.

As for the "I paid for gold service", that's their T&Cs. But what caught my eye is that you paid for Gold? I know there is a nominal $50 sign up fee that almost no-one pays (there are a zillion "get gold free" signups and most corporations get gold service free automatically). I could see a complaint if it was an exclusive thing that cost $300 per year, but it's basically a (expensive) processing fee. Even when I had left my previous company, I had gold service for a decade before I was on to another company that went with Hertz (and they never removed my Gold status even though I had updated my employer and address info).