Disabling automatic top-up stops new purchases under that setting. It does not erase an existing payment or stop its confirmation from being processed. A payment already accepted can still settle and add the purchased credits.
Check the purchase reference and when it began relative to the settings change. Scheduled payments have their own cancellation in the billing portal. If a new automatic purchase started after a confirmed disable, report both times and the reference to support. Do not assume a completed credit purchase disappeared because you changed the policy.