Oh no, it's absolutely not wrong to be upset about poor customer service. That's what warning others about your experience does. At least it warns others of a non-responsive artist. Honestly, this transaction could have easily been fixed if she just said "sorry can't work with you" and sent you a refund. If she felt you were being too pushy, that would have been the correct thing to do rather than completely stonewall you.

It's just not good to say "well I'm mad so I'm keeping what she did complete". Nothing excuses that lack of response, but you don't want a black mark against yourself, you know?