(1) The acceptance of any payment required by the city shall not be construed as an acknowledgment that the amount paid is the correct amount due, nor shall such acceptance of payment be construed as a release of any claim the city may have for additional sums due and payable.

(2) All tax payments shall be subject to audit by the city and an assessment or refund if the payment is found to be in error. Any assessment requiring additional payment and all interest and penalties shall be immediately due and payable. The natural gas supplier shall reimburse the city for the reasonable costs of such audit if the audit discloses that the natural gas supplier has paid 95% or less of the fee owing for the period of the audit.

(3) In the event that such audit results in an assessment by and an additional payment due to the city, such additional payment shall be subject to interest at the rate of eight percent (8%) per year from the date the original tax payment was due.

(4) In the event that such audit results in an assessment by and an additional payment due to the city which the city manager finds to have been the result of intentional acts seeking to avoid payment of the full amount due the city, the natural gas supplier shall be subject to an additional penalty of ten percent (10%) of the total amount of the additional tax payments due.

(5) Any amount due the city as reimbursement for audit costs or as a tax, interest or penalty under section 3.605 or this section shall constitute a debt of the person from whom the amount is due. The city may bring action in a court of competent jurisdiction to enforce payment of the debt.

(6) Any amount due the city as reimbursement for audit costs or as a tax, interest or penalty under section 3.605 of this code or this section may, by declaration of the city manager, be made a lien on the personal property of the person from whom the amount is due. The city may enforce payment of the amount by foreclosure of the lien in any manner authorized by law.