Competiton winning not recieved

Ackermans held a competition on their @ackermans_w page. The competition stated that if you follow the page and tag your friends on the post you stand a chance of being 1 of 5 people to win a R2000 voucher. My instagran account was one of the 5 winners. Since 30 November I have not been able to recieve my winnings. The instagram account won't answer messages. Neither will the Facebook page answer messages regarding receiving my voucher. Iv emailed and called and this has not helped. How sad that this well known brand tells people they win competitions and don't hand over what they promise.