Voucher couldn't be redeemed.

I went to KFC in vangate mall. I had been given a voucher by a family member worth R500. I bought with the voucher in town early hours of sunday and had a remaining change of R260. I tried to redeem the R260 voucher and I asked the manager if I dont have the long number cant they redeem it with my number since it was sent to me. I was given attitude and was told to go back to where I bought my meal initially and that was in town strand street.