Hejsan 👋🏻 , @Muhammad Siddiq
The cost you mention corresponds to the additional user family subscription.
This link contains information on how to sign the invoice. It may be that you pay for a paper invoice and have a fee for it. In that case, it is possible to apply for Autogiro or E-Invoice.
If you don't want extra users, you can easily remove them by logging into the Mitt3 App or in a browser. Or when contacting customer service.
Here you have information on how to apply for Autogiro or E-Invoice if there is a need for it. Unfortunately, the page is only in Swedish.
Regarding invoice questions, you need to contact 3 Customer Service. So they can easily go through your invoice and help you make changes if you want.
Here you have contact details for 3 Customer Service.
https://www.tre.se/support#kontaktaoss
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