Write a respond to this email accordingly. Use a min of 350 words to respond to this e-mail. Mention that usually there is always someone to assist but there was an emergency and needed all staff members at that moment. Also mention, accordingly, that the cleaners always clean unless they put the sign for no cleaning which was the case to their room. Because of this you don't want to meet them with a full refund but want to compensate in a different way. Up to you how and what.