If any operator shall fail or refuse to collect said tax and to make, within the time provided in this chapter, any report and remittance of said tax or any portion thereof required by this chapter, the Tax Administrator shall proceed in such manner as he may deem best to obtain facts and information on which to base his estimate of the tax due. As soon as the Tax Administrator shall procure such facts and information as he is able to obtain upon which to base the assessment of any tax imposed by this chapter and payable by any operator who has failed or refused to collect the same and to make such report and remittance, he shall proceed to determine and assess against such operator the tax, interest and penalties provided for by this chapter. In case such determination is made, the Tax Administrator shall give a notice of the amount so assessed by serving it personally or by depositing it in the United States mail, postage prepaid, addressed to the operator so assessed at his last known place of address. Such operator may within ten days after the serving or mailing of such notice make application in writing to the Tax Administrator for a hearing on the amount assessed. If application by the operator for a hearing is not made within the time prescribed, the tax, interest and penalties, if any, determined by the Tax Administrator shall become final and conclusive and immediately due and payable. If such application is made, the Tax Administrator shall give not less than five days written notice in the manner prescribed herein to the operator to show cause at a time and place fixed in said notice why said amount specified therein should not be fixed for such tax, interest and penalties. At such hearing, the operator may appear and offer evidence why such specified tax, interest and penalties should not be so fixed. After such hearing the Tax Administrator shall determine the proper tax to be remitted and shall thereafter give written notice to the person in the manner prescribed herein of such determination and the amount of such tax, interest and penalties. The amount determined to be due shall be payable after fifteen days unless an appeal is taken as provided in Section 4.92.100. (Ord. 1369 (part), 1964).