does not comply with vodacom adverts

I took out a vodacom contract at the OR Thambo Intl Vodacom Shop. The April specials booklet clearly states that you receive a free wireless charger and clear cover when getting the Samsung Galaxy s6 or s6 edge from vodacom. The manager of the store (who had to be called as he was not present) refused permission for the sales staff to issue me with the clear cover. His excuse is that the clear cover is only for people who pre-ordered. Nowhere in the April specials booklet does it state that the free clear cover is only for people who have pre-ordered. It is available to the general public. I was not the only person who was refused a clear cover by this manager. Someone else upgraded his contract and was also told that he cannot get the clear cover. If it is really that the free cover is intended for those who have pre-ordered, then vodacom has falsely advertised their deal. The packaging of the phone also had a sticker which said that you get a free clear cover which can be claimed from the store of purchase before 30 April 2015. I ended up buying the cover and paying for something which was meant to be given to me for free.