I'm sure people have posted this before but the chances are that you have not been 'hacked'. There is not a team of highly trained bespectacled individuals sitting in a basement somewhere trying to 'hack' into your account details - you are not that important. And even if there were, which there aren't, the last thing they are going to do if they've just spent hours 'hacking' your account is buy things from the iTunes Store.
Here are some useful tips to avoid crying hacker.
1: Are you using a PC? If yes then you've probably been 'keylogged' not hacked, Google it, find out what it is and get some decent malware remover - or buy a Mac. If you're being keylogged then changing your password won't help you as they will be watching every key y o u p r e s s.
2: Do you have kids? So what have these 'hackers' been buying, Haypi Kingdom / FarmVille credits? Really? Where do you leave your handbag these days, on the sideboard is it, half open, with a purse on the top? Little Malcolm may find that very tempting if his birthday is 6 months away! "But, but I asked him and he said 'No, it wasn't me'" You do realise that to a child online gaming is like crack? Don't believe me, take their machine away for a night and watch what happens.
3: Your passwords are rubbish. Yes I know life is complicated but must you use the same password for every login you use online. Your bank, eBay, Amazon if you're using the same password and someone does have it then your ID is their ID. Also, using your partner's name/birthday or your kids' names/birthdays is not secure; You are not the only person in the world that does this. If someone guesses your login details and buys something from the iTunes Store that's not Apple's fault it's yours for having a terrible password. Check this out: If I was to start randomly entering things like star:wars Darth:Vader Spongebob:Squarepants as a username/password would I be getting close to what you are using right now?
4: Human check-out staff. Ask yourself this, who is more likely to get hold of your credit card details:
a: Keanu Reeves and his band of leather clad cyberpunks working feverishly into the night, drinking red-bull and trying to break the 128-bit encryption on secure websites, or
b: The person on the till in the supermarket/petrol station who you 'physically hand your card over to'. It's not that difficult to remember a 16 digit number.
5: Use a credit card rather than a debit card. If you do get your card used by unauthorised persons then your credit card provider should cover you for this. Remember, someone in your house using your card without you knowing doesn't count as fraud.
6: Was it actually you? We've all regretted an impulse purchase but saying you got 'hacked' and you want your money back is just dishonest.
In summary 'hacked' very very very unlikely, 'keylogged' most likely, your password just guessed or someone you know used your card - possibly.