I've had a horror story. Where I wanted to get the special edition of TESIV Oblivion. But because I bought it with TESIII and TESIV vanilla, I had to abandon both copies of the game in order to buy the sale of TESIV oblivion special edition.
Getting this to happen through customer service was an abysmal experience which took like five days. They allowed me to forfeit TESIII and rebuy it at $5 to get TESIV special edition for another $5, because they weren't able to upgrade my TESIV vanilla to the special edition (even though it was only $1.50 more).
For having spent thousands of dollars on Steam for over 10 years, I thought that was really petty of them. Meanwhile, in the Origin camp, the Origin CSRs took my DVD keys over IM chat to add games to my Origin profile. When some of the keys didn't work, they gave me the games anyways (and the upgraded editions as well). I thought that was stellar.