Adding more funds to card is not secure

Hello.

When we check balance we place code of gift card like 3DGY-6F57-7N6G-8VSL.

When we want to add more funds to it we have to do to link like

?pw_gift_card_reload_number=3DGY-6F57-7N6G-8VSL

1. So, any search engine can cache this string ;
2. If I want to send this string to my friends this code can be redeemed.
3. etc.

So can you add Pin code (protection code) to redeem each code, to use it more secure ?

So users can use only code to Fund. But to redeem there should be additional protection.