According to their FAQ's:
"CRI will be able to change your shop date one time per shop. If you mistakenly chose the wrong date or you would like your date changed, you will need to contact your direct Auditor Relations Associate (which can be found at the bottom of the Job Information page for your specific shop) prior to the shops due date."
"Please note: If you wait until after the shop is past due to request the date change, it will be considered incomplete."
You'll have to wait for the scheduler to change the date for you. If your request is prior to the due date, you should be good. You could also try the Contact Us link for assistance.