If any operator refuses to collect the tax and to make, within the time provided in this chapter, any report and remittance of the tax or any portion thereof required by this chapter, the city clerk 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 city clerk procures 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 tile tax, interest and penalties provided for by this chapter. In case such determination is made, the city clerk 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 city clerk 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 city clerk shall become final and conclusive and immediately due and payable. If such application is made, the city clerk shall give not less than five days written notice, in the manner prescribed in this chapter, to the operator to show cause at a time and place fixed in the notice why the amount specified therein should not be fixed for such tax, interest and penalties. At the hearing, the operator may appear and offer evidence why the specified tax, interest and penalties should not be so fixed. After the hearing, the city clerk shall determine the proper tax to be remitted, and shall thereafter give written notice to the person in the manner prescribed in this chapter, of such determination and the amount of the 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 3.20.140. (Ord. 122 §9, 1965).