free gift not showing up in cart when we configure rule

We have a rule set up for $25 free gift card with $100 purchase, and nothing shows up on cart or checkout page for the free gift. Also, how can we set up this scenario:
$10 gift card when you spend $50
$15 gift card at $75 purchase
$25 gift card at $100 purchase

I understand that we’d need to create 3 ‘free gift’ products, but how can we prevent someone from getting all of the free gifts with a $100 purchase (ie they get $10, $15 AND $25 free gift with $100 purchase, when they only should get one $25 gift)?