2nd : You have got to stop thinking everyone will do everything for you. It is YOUR horse so YOU are the one responsible for the care. Just because someone agrees/offers to do something for you/your horse does not mean it will be done/happen. It is your responsibility to check up on it. Get that persons phone number so you can call and double check if it was or was not done.
What would of happened if the blanket had been removed and you had come out to a normal day and the horse wasn't sweaty? You would be upset the blanket was off.
Some barns have temperature charts to ensure everyone is on the same page. I have my boarders make up their own minds. That way they are not mad at me.