Hello AWR,
Have you ever been in " Customer Center " => " Bills & costs " => "Bills "?
At the swisscom home page, click on the right corner up, " Customer Center ". The icon cercled and pointed in red.

Log on with your Swisscom Login. If you don't have it yet, set up one clicking on "Setting up Swisscom Login"

When you logged-on to " Customer Center " choose "Bills" from menu colomum on left hand of the page,

After clicking on the traiagle pictograme for "show&hide", each bill and statement can be seen and dowloaded clicking on PDF icons, shown here cercled and pointed in red.

If you need a deatailed TVA statment, you may need to contact, we recommend you to contact the support directly: https://community.swisscom.ch/t5/help/faqpage/faq-category-id/swisscomsupport#swisscomsupport.
or: https://www.swisscom.ch/en/residential/help/contact.html
With best regards, tn