When did you take out the subscription ? if you were informed of the cost now and from 01/11/2020 then you can't cancel, your wording makes it sound like you just ordered and the order confirmation states how much your ongoing charges are from 01/11/2020, the order journey will state the upcoming price change, did you order by phone or online ?
If you signed up without being informed of the price change, for example subscribed weeks earlier then you do have the right to cancel the BT Sport app without early termination charges.