We've only had the opportunity to use our SH benefit for OBC on our cruise in Dec 2021, but that was with Princess. In that instance, our credit showed up in our booking details (I think it was in same place where we could find our price, taxes, grats, etc.) although, I'm not sure we got a confirmation email... IIRC, it just appeared. Are you saying there is no way to verify the OBC online before you sail, other than an email?