I need to stop the 3.99 payment for the additional storage. How do I do that

Contact your card company and cancel the charge or call apple.

Are you referring to iCloud storage?

iCloud storage upgrades and downgrades - Apple Support

Just as you upgraded the storage plan, you can downgrade it to a lower-priced or a free plan. The method is the same.

Please ignore the post by Averythomas - it is completely invalid. Follow the instructions in the Support Article provided by Babowa.

Cheers,

GB

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