Error There seems to have been an error initializing or updating your transaction.

I've had a similar message when trying to purchase through Steam itself. It was because I was buying a lot in separate transactions (multiple gifts of the same game). In my case, this was a fraud protection (contacted support). I'm not sure if you had more than one transaction that day, but perhaps you had a similar instance. In my case it corrected itself after a couple of hours.... so maybe you have even purchased this by now. I do agree with contacting support... while you wait (how ever long that is) you can check to see if it will go through every couple of hours.

Also, have you Googled the error message?

Lastly... here is a time killer.