How do I dispute charges?

While I do allow my grandson to make very small purchases while using my phone, he doesn't have my password. However, while we were on vacation and away from the device he uses, major charges were made on my Apple ID account. I had to change my credit card because I believe someone hacked into my account. Apple shut down my account and sent a majority of the claims back to my CC. There is apparently no easy way to talk to someone about this so will I have to simply eat these charges???