How to stop automatic payment please

Cancel the subscription -- see: How to cancel a subscription from Apple - Apple Support or if the charge is for an upgraded iCloud storage plan, cancel by downgrading to the free 5GB plan. See instructions in: Downgrade or cancel your iCloud+ plan - Apple Support

If the above doesn't help, be aware that this is primarily a user-to-user support forum; other Apple users like you. We don't have access to information about charges to your account. See each of the steps in the following instructions. They include information on contacting Apple Support if the other steps don't help: If you see 'apple.com/bill' on your billing statement - Apple Support