(6)The pendency of an appeal under this Section shall not operate to delay or prevent the levy and realisation of any tax or instalment thereof payable in respect of any holding according to the order of assessment under appeal but if by the final decision in the appeal it is determined that such tax or instalment ought not to have been levied or realised in whole or in part, the Chief Municipal Officer shall refund to the person from whom the same has been levied or realised, the amount of such tax or instalment, or the excess thereof over the amount properly leviable in accordance with such final decision, as the case may be, or adjust such excess amount against any future demand.