The following article contains an answer for the question: Who does Curtis think is ordering him to stop the taxi? , can you please find it? 

Elliot Hopper is a workaholic widower who is about to land the deal of a lifetime at work, which he hopes will win him a promotion and a company car. After he forgets his daughter Diane's birthday, he attempts to make it up to her by promising her she can have his car when he secures the deal at work on the coming Thursday. After being persuaded to give the car to his daughter early, Elliot must hail a taxi from work, which is driven by Satanist Curtis Burch, who drives erratically and is of control. Attempting to get the taxi stopped, Elliot announces that he is Satan and commands him to stop the taxi, and also attempts to give him his wallet. Shocked to see his "Evil Master", Burch drives off a bridge and into the river.
Elliot emerges from the accident scene, only to learn that he is a ghost when a police officer fails to notice him and a speeding bus goes straight through him. When he gets home he discovers that his three children can see him, but only in a totally dark room, and they can't hear him at times. He struggles to tell them what happened when he is whisked away to London by paranormal researcher Sir Edith, who tells him he is a ghost who has yet to enter the afterlife because "they screwed up"; his soul will not cross over until Thursday.
The pressures of work and family life lead to many comedic events, as Elliot attempts to renew his life insurance policy and complete his company's merger, so his family will be provided for once he crosses over. One day, he must choose between staying in an important work meeting and helping his son with a magic trick at school. He eventually decides that his family's happiness is more important and walks out on his furious boss, Mr. Collins, who later smugly fires him. Dejected, Elliot reveals himself as a ghost to his love interest, Joan, whose initial shock soon turns to sympathy.

Satan