Hi,
I will request you to contact our billing/sales team for more information, billing/subscription support is free for all Azure customers, you can create a free ticket here: https://portal.azure.com/#blade/Microsoft_Azure_Support/HelpAndSupportBlade/newsupportrequest.
Also check the Mail Address of the sender sometimes it is phishing mails to lure you into providing the Credit card details, so advice is to double check and confirm if it is from genuine sender.
Hope this helps.
JS
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