Vouchers don’t work on the Nando’s app

I used vouchers on the Nando’s app and made a payment with my credit card but when I went to collect they told me that their system shows I didn’t use any vouchers the payment online went through with the vouchers we didn’t get what we ordered cause it said we didn’t pay I wouldn’t recommend using vouchers on the app when we go in the app it says we collected our order when we didn’t even get it.