Terrible customer service 😡

I recently won a voucher from debonairs pizza competition on Facebook platform. I was sent the voucher of R150 in Direct message. I tried several times to redeem the voucher on their app and it gave me an error message of "Invalid voucher". I tried to reach out find whats really going. Then i was told to reach out to wi code company, the which they work them with vouchers. I feel like debonairs pizza is not taking me seriously.