Won vouchers *2 and it does not work

So in December myself and my husband both won R150 kfc voucher each by playing the Fryhard AR game. When we tried to use the vouchers it said that it was invalid also the voucher codes was the same. I contacted kfc via Facebook and they have been telling me that they are going to get back to us and took our contact details they said on one message that we missed a call which we did not. For months when I ask them they say they will get back to me and they never do I have all the messages.