Still debiting 18 months after cancellation

Cancelled my line 18 months ago when I moved out of the property, asked more than two people on their WhatsApp chat to confirm. FF to 16 months later and these ****ers are still debiting me. After an hour long call and sending them screenshots of me requesting and following up on the cancellation, they just tried to debit me again a month after all of that. Now their chat agents are non responsive and dropping my chats. Noone will help me. Their internet speed was terrible and connection unreliable, but their customer is bottom of the barrel. Absolutely the worst experience.

Looking at the amount of similar complaints, I am thinking I will never be able to get this account actually cancelled and my money refunded because they clearly dont five a damn!