@Mimoune Djouallah Welcome to Microsoft Q&A, Thank you for posting your query!
The below mentioned link will help you in calculating the price of Azure products along with their features available. https://azure.microsoft.com/en-in/pricing/calculator/
For complete detailed information on Azure Files Pricing, See here
An important article to read on the Azure Files billing models can be found here: https://learn.microsoft.com/en-us/azure/storage/files/understanding-billing.
Transactions are operations or requests against Azure Files to upload, download, or otherwise manipulate the contents of the file share. Every action taken on a file share translates to one or more transactions, and on standard shares that use the pay-as-you-go billing model, that translates to transaction costs. See here
If the issue is still not rectified, for more specialized assistance on this I would recommend to contact Azure Billing team, it's free, and it's the best choice for you. They could provide provide their expert guidance on your scenario based on their experience. Thanks.
Hope this helps!
Kindly let us know if the above helps or you need further assistance on this issue.
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