I finally managed to log into the chaos that is the Swisspass / SBB online service and when I did, I found that there was a 15-franc penalty fee for the alleged late payment of my half-fare pass bill. The thing is, I not yet received the bill for the renewal of my half-pass fare.

I find it pretty cheeky of the SBB to slap me with a penalty fee for late payment of a bill which I never received.