My wife’s add-on had the same number so cancelled it and requested for a new card again which arrived as fresh as day before yesterday!!
I opened the packet ( it came with new card number and again a new PP), logged into My-Cards, set the PIN & set the card control as well. All OTPs came to my number only.
KINDLY CLICK ON YOUR NAME INSIDE MY-CARDS - ITS A DROP DOWN MENU WHICH SHOULD REFLECT THE ADD-ON TOO.
Thereafter, logged into GyFTR with her phone & card number (my number’s quota of 10K Amazon GC already exhausted for this month) and was able to buy another 10K worth Amazon GC.
HOPE THIS HELPS!
Regards