Nappies for Babies

Being a Discovery Medical aid member we received discount cards on nappies at Toys R Us. When we started using these cards we bought Pampers nappies and we received discount on that. Now all of a sudden we went in to buy nappies and we were told that the discount only works on Huggies nappies and not with pampers. So the question is how the hell did Toys R Us let us buy Pampers nappies and get discount in the past and now they tell me that its only on Huggies that we get discount????