Thank you to the staff reaponded and those who helped.
Here is my experience
First of the bat it isn’t simple. The SBB staff had to contact manager , then colleague etc. They did changed the date and printed a paper copy of the HF card for 10CHF. Which is again a pain to lug around. But I was grateful nonetheless.
The reasons they were brining up were belief that I have not used the card already. I produced my passport as evidence. The stamp in that doesn’t seem to be enough as there were workarounds, apparently. So buy the HF card closer to the arrival date in Switzerland. These are my few cents.