Best answer by mattj3135
Updated 06/05/2020 - If you want to know more about the Refer a Friend scheme, check out our FAQ about it here!
It could be down to a slight typographical differential that has prevented the system issuing the vouchers.
Have you reached out to Boost customer care team? If you have your friends email and supply address to hand along with your email address when you contact them they can check the system and arrange for them to be sent ASAP.
Alternatively you can PM one of the lovely moderators