18. Save as otherwise provided in this Act- (i) on payment or the amount due on a Government security on or after the date on which payment becomes due, or (ii) when a duplicate security has been issued under section 10, or (iii) when a renewed security has been issued under section 12 or section 13, or a new security or securities has or have been issued upon conversion, consolidation or sub-division under section15, the Government shall be discharged from all liability in respect of the security or securities so paid or in place of which a duplicate, renewed, or new security or securities has or have been issued- (a) in the case of payment-after the lapse of six years from the date on which payment was due; (b) in the case of a duplicate security-after the lapse of six years from the date of the publication under sub-section (3) of section 10 of the list in which the security is first mentioned, or from the date of the last payment of interest on the original security, whichever date is later; (c) in the case of a renewed security or of a new security issued upon conversion, consolidation or sub-division-after the lapse of six years from the date of the issue thereof.