Recently we got an automatic coupon from a major retailer. One of those "Spend $x on a category and get $y back".
The problem was that their system ran into a bug that actually charged us the coupon amount in order to get the coupon. It became a "Spend $x on a category, get $y back after we charge you $y".
As you can imagine, explaining that to their chat bot AI and then customer service took a lot time. We're not even sure if they'll actually fix it for next time or if it'll come back.
So if you offer coupon codes, make sure they are simple to understand.
Any complexity in your coupons beyond "save $x" or "save x%" will cause some customer confusion and loss of revenue. Getting to checkout only to find a coupon doesn't work is a quick way to cart abandonment.
Directive: Keep coupon qualifications simple.
Eric Davis
Find out how your Average Customer behaves
Learn who your Average Customer is and how they are buying from your store.