Any purchaser who shall fail to pay the tax imposed in this article at the same time and in the same transaction with the payment to the seller of the utilities service purchased shall be liable to the city for a penalty equal to one percent of the total charge for the utilities service for each day of the default, which penalty shall be collected by the seller and paid over to the city. If any seller shall discontinue the service of a purchaser because of the nonpayment of the tax, it shall be unlawful to restore such service until the tax and penalty shall have been paid in full.