nothing will let me cancel Starz

A family member subscribed to starz through xfinity without my knowledge. My flex box says I have no subscriptions so I can't cancel it there. I try to use the xfinity app to cancel and it tells me to use the ai assistant to help for that. It gives me instructions and a link so I click the link. That link tells me I have to sign into the xfinity site and use the same ai chat to unsubscribe. When I go do that it tells me to come back a specific date during certain times. It does this everytime I try, despite it being the dates and timeframe it tells me. This is infuriating. I have to pay for it a 2nd time because I can't cancel it! I'm already overpaying for the quality of internet I'm getting, this on top of it has me about ready to cancel my account!