Amazon is sending out $30 gift cards to of their Visa cardholders for a coupon code which didn’t work properly.
Amazon had a special offer for cardholders to get $30 off $150 on Prime Day. The offer wasn’t working the last half of the day, probably unintentionally, to the frustration of many.
To rectify this, Amazon has automatically loaded a $30 gift card balance to the accounts of effected cardholders. Some reports indicate that even those who didn’t make $150 purchase, but attempted to do so, also got the $30 credit. Others indicate that only those who actually ordered on Prime Day got the $30 gift card.

Image from Reddit https://www.reddit.com/r/churning/comments/4stks0/amazon_credited_30_towards_my_account_for_prime/
I’m not sure if Amazon did this for legal reasons or customer satisfaction reasons; more likely the latter. In any case, most other companies drag their feet and eventually cave. Amazon does customer service right.
If you also had this problem with the $30 promo code not working for you, try chatting with Amazon and requesting compensation; they might be able to issue the Amazon credit manually.
