Sichifuss16 this is not Swisscom, but Swisscom customers helping Swisscom customers.
You can download the bill from MySwisscom: https://www.swisscom.ch/myswisscom/billing
and also view all bills backwards up to 24 months. There is a charge for converting the bill by post, which you can also change in MySwisscom.
or request it here via chat: https://www.swisscom.ch/de/privatkunden/hilfe/kontakt.html#cascadingTabs%5Binner%5D=tab_1643987857841&cascadingTabs%5Bouter%5D=tab_1643984430352