Travel Voucher on Upgrade Package

I recently upgraded my Vodacom contract online and took up an offer for a new S8. The deal was supposed to include a Flight Centre travel voucher, but of course when the phone arrived the voucher was nowhere to be seen. (It wasn't even listed on the invoice). When I contact the call centre the responses either vary between "it is the wrong department" or "We have noted your enquiry and will get it resolved". Two weeks have passed and nothing has happened. Vodacom, what is going on? Are you falsely advertising deals? Are the vouchers getting ******? Please could someone contact me.

Thanks and Best Regards