A government authority may obtain financial records pursuant to a subpoena if:
(1) There is reason to believe that the records sought are relevant to a government investigation;
(2) A copy of the subpoena has been served upon the customer or mailed to his last known address on or before the date on which the subpoena is served on the financial institution together with the following notice:
(3) Ten days have expired from the date of service of the notice or fourteen days have expired from the date of mailing the notice to the customer and within such time period the customer has not filed a statement or a motion to quash in an appropriate court, or the customer challenge provisions of section 408.686 have been complied with.