I only had House of Wolves for two weeks before The Taken King was released, and within a week Patch 2.0 removed huge chunks of the content, so I called up Xbox Live and got a refund. I couldn't get a refund for The Dark Below as I had it for 9 months, but I hear if you are persistent and polite they will still give you a refund. For vanilla Destiny, I am getting a 50% refund from Amazon, which they offer for late returns of opened games, as long as you have a reason.