If any operator shall fail or refuse to collect the 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 Director of Finance 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 Director of Finance 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 same and to make such report and remittance, he shall proceed to determine and assess against such operator the tax and penalties provided for by this chapter. In case such determination is made, the Director of Finance shall give 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. (Ord. 1471 § 1, 1973; Ord. 1339 § 1; Ord. 986 § 1; prior code § 7.309(1)).