If not paid for in full at the time of purchase, plots or niches may be sold upon the following terms: one-third (1/3) cash on the day of sale, the remaining two-thirds (2/3) within one (1) year from the date of the sale. Such deferred payments shall be secured by the promissory note of the purchaser, and such notes shall not bear interest until due. No deed shall be delivered until the entire purchase price has been paid. No marker, memorial or niche plate shall be placed, nor shall a burial be permitted on such plot or in such niche, until the full purchase price has been paid, and in the case of a burial, a burial permit has been received by the Director of Public Service. Upon default in the payment of the purchase price of any plot or niche purchased after June 1, 1968, the City shall have the right, upon first giving thirty (30) days written notice by registered mail addressed to the purchaser of record or, if the name and/or address of such purchaser cannot be ascertained, by publication for one (1) time in a newspaper published in the City or the County, to declare the sale of such plot or niche canceled. Thereupon all rights of such purchaser to such plot or niche shall be terminated and any payments thereon shall stand forfeited to the City as liquidated damages for failure to purchase such plot or niche.