Charges from iTunes

On my bank statement I’m getting charge so many times from iTunes from 2/3 dollars to 40

and it’s all the time and I am not letting anyone charge on my iTunes account. Why am I being charge for purchase it I did not make And how are they doing it. This is costing me close to 100 dollars in 2 weeks. And it’s been going on for awhile. I can’t get anyone to help me and get me my money back. I’m about to get rid of iPhone cause of the iTunes bs. Please help me