So the voucher is not available for quite sometime now. But you can redeem the voucher for points at your usual petrol pump where you'd redeem the voucher. You just have ask the person to redeem reward points and they'll do it. If not, you can ask the person to follow this method .
Please note that Tap and Pay doesn't work for redeeming points, at least in my experience.
Mark it as a solution if it did help you out 🙂