It took me a while to work out how to pay bills in Switzerland too, but once you do work it out you’ll realise how easy it is.
For online banking you just need the bank number and a reference number.
The bank number is typically nn-nnnnn-n and the reference number a long string of digits. You can cut and paste these.
I use PostFinance and their phone app has a function where you point the camera at the pink slip (even if it’s just on your computer monitor) and it’ll read the details automatically. Cool.