how to cancel expired subscriptions?

so i accepted a free trial for an app, and i forgot to cancel it in time. the expiration is september 26, which was yesterday.

i cannot download any apps without it directing me to selecting a payment, which i’ve already input a payment app in (the balance is only 100), but now that it is “expired”, i tapped in to buy a tiktok promotion which the price is 100, and i received a message saying i did not have enough balance to pay 399 (the now expired subscription), when i didn’t even attempt to pay for the subscription. how do i cancel this?