What do I do if my roommates refuse to confirm my move-out date?

Do you use SimpleBills on your own and the utilities are in your name or a roommates' name?

If the answer is yes, we must have roommate confirmation to change your move-out date and release you from the utility responsibilities. If they refuse to confirm your move out, you will be responsible for usage that occurs during your start and end date as established in your contract. SimpleBills holds a firm policy with this to protect you and your roommates from being charged unfairly.  

Why can you not accept my property manager's confirmation?