Many users are having this issue now that U.S. and EU courts have forced Apple to give up control of App Store purchases. You can now either get an app off of the App Store, or side loading an app directly from the vendor.
Either way, those vendors can now charge you directly and the charges do not appear anywhere in Apple's system since it didn't go through them.
Apple predicted this would happen and vehemently fought the courts against them interfering with the operations of a private company. The courts didn't care/listen, and now consumers have this mess.
A common scam is to offer something for just a couple of bucks. You give your credit card information and figure you're done. Except, the crooks then apply a subscription fee without asking if you want one, of even disclosing there is such a thing.
Contest the charges with your credit card company and have them reversed if possible. Also have them cancel your current card and issue you a new number so the crooks can't keep charging to your current card.