False coupons rewards

I made a purchase of grocery worth R2023.90 on the 25th August and I was rewarded with R200 voucher to be used on from the 9th on my purchase have 3 chickens of which was going with tactic rice my way I realized I haven't picked up the rice that goes with the chicken I had to return back to the store and they gave me a second copy slip when I went back to use my voucher they denied me because the second slip doesn't have a voucher number now what do I do to use my voucher and why the reprint doesn't have the voucher number I don't have the teared copy that they claim they have given me so now does that mean they can find a way to let me use my coupon