Commissions

If you want customers to come when you're there then be subtle about it. Never tell the customer when to come, they don't care who gets the commission. They will come when it is most convenient for them.

If a customer doesn't bring your card in then that's just tough luck. That's the way it works. Best you can do is emphasize the importance of bringing the card back in when they decide to make the purchase. I'd even make up a story about how your performance is ranked by turning in that card.

In the situation of the specific example you gave. You need to stay on his *** about it or go to the manager. If everyone involves openly admits it was a mistake then it should be corrected.

Other than that, this is sales and commissions. Your team members will lie, take your card and throw it away and cut your throat to get the commission.