In the event a wrecker service operator is requested by the police department to make a call and the operator agrees to make said call then such operator shall proceed immediately to the scene where he is directed and shall be given a reasonable length of time in which to reach said location. If the wrecker service operator answering said call has not reached said location within a reasonable length of time then the officer at the scene may proceed to call the next wrecker service operator on the list and that operator shall have priority in that particular call. In the event that the wrecker service operator called fails to comply with the provisions of this section by proceeding to the designated place within the time specified above then this wrecker service operator shall be removed from the top of the list and placed at the bottom of the list. This section shall not apply where the operator's name at the top of the list is called and he advises the officer requesting the wrecker service that he will be unable to make said call nor will it apply where there has been a delay caused by some act or commission of another person other than the wrecker operator or his employees or by an act of God.