Harassed

This gym has been harassing me for 3 years now. My contract expired in Nov 2018, but they continued deducting . Feb 2018 I went to cancel. They gave me a slip for cancellation and that was it. Few months they called and emailed saying I must pay. I called them back telling them it's actually the other way around. They owe. 2 years later one of their employee sends me a what's app with my personal info home address, work, banking and id. How is my personal info easily available to strangers? If I get ****med this will all be on this gym