In authorised debit

I have made several requests to On-Air Tv , they need to stop subscribing us to Rescue box. I have forwarded numerous emails to their support centre begging them to please unsubscribe me because I didn’t signed up for Rescue box. To my surprise they debited on my account. I am very angry at this point because every month I need to reverse that subscription. Please assist on how do I go about cancelling this