For me something very strange happened. Apple charged me two times when they reserved the amount for my imac. first they took the whole sum of the imac then a few secs later they reserved an amount of about $400+ for nothing I bought...
I have called them but haven´t heard anything back. I never accepted this withdrawal, kinda weird they can do that...I find such things rather serious and would expect an instant customer service to sort it out - which I haven't got yet.