Honour my voucher

I went to Cedar Square store on 300 May 2025 to redeem a voucher from my Smart Shopper card which was expiring on the 31 May 2025. There was a Smart Shopper issue and my voucher was not appearing within personal discounts for me to redeem. The staff at the store did her best to assist but ultimately I had to log a query with customer service. Customer service responded today to say my voucher expired and are not offering compensation as I couldn’t redeem due to their system issue. They should honour my voucher as compensation.