Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
I wonder if it is an XBox game charge of some sort. There are no Office charges that are $9.99 per year.
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Unfortunately the description of charges from MS are consistently vague, "better" for MS.
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Here is the "official" way to find out about billing charges:
How to investigate a billing charge from Microsoft
When you see unexpected charges from Microsoft in a statement from your bank, credit card, or any other payment provider, we want to help you resolve your question as quickly as possible.
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You will have to jump through the hoops Hilla suggested to contact "new & (dis)improved" MS Phone support.
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Since you have a 365 subscription you are PAYING for PHONE support, so don't let them give you the excuse they can't support you. A few people have reported that happening to them