Sorry for the hassle, I'd expect a little better from Blizzard.
At least you were able to cancel your original order, wouldn't want you stuck with a game you had no interest in.
Yeah, I don't know what Blizzard's problem is. So far I have ordered Diablo 3 three times with one credit card and all three purchases have failed and they downgraded the account. Fortunately, the character progress was not lost. So I have tried buying it a fourth time with a different credit card. If that one fails then I am probably just going to buy a key from someone.
Blizzard really should figure their crap out so they can take money from people. Absolutely ridiculous.