Hello Rafiki52
Firstly, welcome to the SBB Community.
You have missed setting the validity date to other than [today].
and the offices are closed right now
Nope, SBB can be reached 24/7 by phone: +41 51 225 56 78 (waiting times are possible).
Contact SBB asap; otherwise you will have to repurchase a new Swiss Half Fare Card.
Kind regards,
Roland