Who do I contact about being charged twice?

Hi all,

I made 2 purchases from iTunes sometime last week at a cost of $2.19 each, but for some reason Apple iTunes only charged me $2.19 for one purchase and not both. A week later, I noticed I was charged $4.38 when I already paid for one of the 2 songs the previous week. My bank statements also show 3 recent transactions from iTunes Music Store Australia when iTunes only shows 2 recent transactions from iTunes Music Store Australia.

I'm not saying Apple.Inc is a criminal or anything like that because they're not, just saying there might have been a mistake where the system may have thought I wasn't charged for either songs when I did in fact get charged for one of the songs the previous week. We all make mistakes from time-to-time and I can understand this quite clearly.

Thank you for taking the time to read and reply,

Jan H. Dacion.