How to stop unwanted webinar invites I never signed up for

A company that I used to subscribe to receive a service from, but I have since cancelled, is continuing to add my name and email details to register to new webinar series. The company is then using this as an excuse to try to continue to charge my credit card to attend and view the webinars.

I never signed up for the webinars and I do not want to receive these spam emails.

How am I able to unsubscribe from these webinars that I never signed up to? (a fraudulent company is using the invites as an excuse to try and charge me for attending the meetings!)