Coca-Cola Fan Can Be A Bok

I recently won a springboks retail voucher on A fan can be a bok competition the voucher was worth R1500 when trying to redeem the voucher it told me limit reached and I never used the voucher Springboks retail told me to call Coca-Cola so they can help me investigate the matter when I called Coca-Cola they told me the voucher was redeemed 2 days later after winning it but I know it's impossible because my phone was off those days and I didn't redeem the voucher when I send them an *** asking them to help me investigate the matter further I got no response I sent them 2 emails with no response I am certain I didn't redeem the voucher how can the voucher be redeemed when I didn't unless they gave me a duplicate voucher.