What should I do if the merchant did not issue a stamp upon payment? NTUC Link July 12, 2019 02:55 Updated Do remember to present your phone to the merchant upon payment so that he/she can issue you a stamp. Related articles What should I do if the stamps I have accumulated are missing? My LinkPoints are not credited. What should I do? What is Plus! Exchange? Can I use my phone like a Plus! card by tapping it in store? Can I transfer my LinkPoints?