I've pretty much written off any hope of having it corrected, so all I can say is caveat emptor.
Let the hateful responses commence.
What is this supposed to imply about the purpose of this thread?
I'm afraid there isn't anything that can be done about the problem that arises when the server loses connection while someone submits a reward code. You're not the first one I've seen with this problem, and I've seen it befall others submitting far more valuable reward codes.
I can say the following with confidence, though not certainty:
Reward codes are good for one use, and one use only. When you submitted yours, the server received it and checked it off as "used". This made it so that all future submissions of that same code would not yield any rewards. (I think both you and I can imagine the disastrous possibilities of a reward code being reusable an infinite number of times)
Unfortunately, you experienced a connection issue at the same time, so instead of the reward window, you got the "default" message that appears when you have a connection issue (the very same that appears when you try PvP1 or T50 without an internet connection).
Then, why you submitted the same code a second time, the server believed that you had already reclaimed your reward before and denied you your second attempt.
Since this is a problem Zanz would definitely had fixed if he could (he is a
really nice guy!), I can only suspect that the cause of the problem is written too deeply inside the game's code to be either safe or convenient to change.
Sorry I can't help, and a tip of my hat to you for donating in the first place.