http://www.tele2.ch/mobile/ger/index.html
This is the German page and works perfectly. It's the page about the MVNO on Swisscom. But it's true, it's not linked anymore from Tele2's main site, it just shows the page you told us, which is in German only.
So it seems that Tele2 has no prepaid offers anymore, by now.
Keep us informed!