Legal Advice- Lawyer / Facebook Ads Hack and Charges

I am looking for legal advice. My account was hacked. A client that gave me access to their ad account reports unauthorized charges for ads created from my ad account. But I did not do it. There are other strange activities in my Ad account (one account is gone, and another has multiple attempts to access it from very strange emails).

I need legal advice to respond to Facebook and to how to handle this.