How to highlight changes/updates on a booking/reservation that requires accept/decline?

Target audience: people who don't use internet and are not good with using smart phones or computers. Where: digital service on a mobile website / mobile app

  1. User receives a reservation, which they can approve or decline. With details such as date and time, duration, special instructions.
  2. In case they approve, the reservation is confirmed, and all good.
  3. If the reservation is updated (date, time, duration and/or special instructions change), they will receive an email about the changes (overstrike on the old values, new values displayed next to old values with a red font). And they need to accept/decline on their account online.

PROBLEM: How to highlight the changes to the user as clearly as possible, on their account when they log in?