If the voucher was swiped on the same day, log in to FaveBiz Staff Mode and check if the redemption was successful before serving the customer. You can do this by checking to see if the Voucher Code matches with the voucher in customer's app. 

However, you are not obliged to serve the customer because the customer is not following the Customer Policy. You may also direct the customer to contact our Customer Happiness team via live chat in the Fave App. 

Steps to contact Customer Happiness: 

Ask the customer to open the Fave app, simply click on Me > Help Centre > and “Talk to us” to initiate a live chat! Our agents will assist you from there.