Hello Wheewoixiett16
Welcome to the SBB Community, a customer-to-customer help forum.
It is not possible to cancel the Swiss Half Fare Card, even more if the validity start date is already in the past. You may check with SBB for any exception to this rule. Please call SBB if you purchased the Swiss Half Fare Card from SBB: +41 51 225 78 56 (24/7, waiting times may occur).
Please kindly note, a text in all caps is very hard to read, and in our culture, writing in capital letters is understood by the audience as shouting. You should refrain from it if there is no reason.
Kind regards,
Roland