I'm getting calls of unauthorized charges on my apple account. What do I do ?

I have never heard of Apple calling about that. It is therefore likely phishing.

Scams (e-mail, text messages, and phone calls) are getting very good at closely imitating true Apple communications. Always be cautious. Here are some guidelines:

Identifying legitimate emails from the App Store and iTunes Store - Identify legitimate emails from the App Store or iTunes Store - Apple Support

Recognize and avoid phishing messages, phony support calls, and other scams - Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Apple 'How to identify, avoid, and report phishing' video--> https://youtu.be/SR3Z3fXXjfw