Known Coupon issue?

I just ran into this coupon problem today so I’m just trying to find out if this is a known issue or if I set it up wrong.

I created a coupon for $100. The customer only used $49 of it. Now it says it’s unusable. So does it not subtract the 49 from 100 giving my customer 51 left or did I create it wrong?

Coupons are single-use for the order with no stored value of the unused portion. Gift certificates do offer a stored value.

If you are running 1.3.5 or greater, take alook at the Promotions which allow you to create a Gift Certificate as a promo.I have not tried this promo configuration to see how exactly it works and it may not allow use of the created gift certificate on the current order.