Our vouchers are sent out automatically by our marketing team. Each one is assigned to specific accounts based on that account's history and activity with us, so they cannot be requested, and our Customer Care team cannot issue, resend or look up a code.
If a voucher has been assigned to you, you will find it in your notification centre: tap the bell icon in the top right corner of the home screen. It will be there whether we sent it by push notification or by email.
If your notification centre is empty, there is no voucher on your account at the moment. We send new ones regularly, so do check back.