I don't know what SHABA stands for, but to be approved for the Sandbox you must be booked at a SHABA Plus hotel - it is some type of certification that proves their staff is vaccinated and meets other requirements set by the government I believe. You have to pay for your stay and then the hotel generated a confirmation that you submit to the Thai Consulate/Embassy in your area. That confirmation will have the exact days that you have registered and paid for. In my case, it was originally for Oct 5 - 19. I paid for those dates. As soon as the change was announced, they emailed me to ask if I wanted to now just stay for 7 days. That answer was yes, so they sent me a new certificate and refunded me half of the money already paid. It was instantaneous. That hotel confirmation is supposed to be shown along the way when you travel, but I think it is really only needed to get the COE. Without it, my understanding is that you will not get a COE in the first place for the Sandbox. Hope that helps - Cheers