Pay back the money from Discovery Vitality Shoe Booster

I activated shoe booster on 2 December 2017 and bought running shoes from Sportsmans Warehouse and swiped my card at the till . I followed the steps as set out in the "shoe booster rules" for 2017. As of today I have not received any cash back even though I have achieved all of my fitness goals. I made enquiries and provided proof of purchase. I was told by Vitality that they didn't register my healthy gear card at the till point. I feel that the responsibility lies with Discovery Vitality to provide proof that I did not swipe my card. If there is a fault in the system and it does not register the swipe of the Healthy Gear card, it is Vitality's issue, not the client's.