Voucher bought in 2021 which expires in 2020 sold to me

I bought a gift voucher for my nephews birthday. The shop assistant at the Brooklyn branch according to them swapped my voucher with someone else's. But first they said the voucher was used at the Grove, but my nephew is in Cape Town. The voucher was bought February 2021 and the expiry date is December 2020! Totally embarrassing experience for my nephew and an annoying one for me, as I have gone back to the shop twice and nothing was sorted out and sen two emails to customer services. The level of incompetence is so annoying and frustrating!