Hi Rob,
In order to change the payment frequency from yearly to monthly for the Office 365 Enterprise E3 subscription with 1 license, we need to do the following steps:
1. Set original subscription status into “In Grace Period” (Action carried out by our related team)
2. Customers need to click “Purchase Service” link on the Admin Overview page of portal
3. Customers buy the same plan with the desired seat count
4. Customers choose the desired payment method from portal during purchase process
5. Once the new subscription is visible in portal, cancel the unneeded subscription (Action carried out by our related team).
Please help us confirm if you want to change the payment frequency. If yes, we will help you change the original subscription status into “In Grace Period” from our side.
Best Regards,
Anna