But fun to play along if you have nothing better to do!
If you have need of a gift card for a present, buy it, send the 16 digit number but alter a couple of numbers is the middle, so it shouldn't work!
If they come back you can claim a typo and correct one of the numbers and show your concern that they have tried to 'cash' it before the meet.
Send the new, partially corrected, number, sit back and wait!
Of course the more numbers that you originally alter the longer you can play the game!
Waste their time for a long time.