Hi René Barnickel, I want to help you with your question.
If I understand you right, you had a problem with your credit card and the invoice couldn't be paid. But now you clear all problems and you paid the open invoices, but the subscription is still deactivated.
I would recommend reading the following article if it helps you already.
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/subscription-disabled
Otherwise, I would open a support ticket at the Azure support https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/resolve-past-due-balance#:~:text=If%20you%20know%20your%20payment%20has%20been%20processed%20but%20your%20subscription%20is%20still%20disabled%2C%20contact%20Azure%20Support.
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