Which of my coupons cost me the most?

The Coupons & promos panel on your Dashboard. It lists which codes were used in the range you chose and how much discount each gave away, so the dear one is the one with the biggest figure next to it, not the one used most often. The monthly statement adds every coupon redeemed that month on its Summary sheet. Judge a code by the orders it carried and what those orders were worth, not by how many messages went out about it. Change or switch a code off under Marketing → Coupons.