Howick - Poor Service

I have recently (24/11/2017 - Black Friday) upgraded my contract with MTN. As per the adverti*****t, I am legible for a R300 voucher for any Samsung or designed for Samsung accessory. Firstly, the manager of the store is based at a different branch (Cascades, PMB) who informed the staff that the voucher is only for a phone cover. I had contacted MTN head office on Friday (08/12/2017- 2 weeks later) and was informed that the staff member was to lodge the complaint on to the regional manager on the day via email and i should be copied on the email, which to date i have not received. I do not want a cover for my phone as the phone i received come with a cover, i would like to use the R300 voucher to purchase a screen protector! When i was in the store, the staff member assisting me called the manager (at a different store), who rudely insisted that the voucher is for an original Samsung cover! Please can i get this matter resolved urgently as this would be deemed as false advertising if i am unable to use the voucher on any accessory as advertised! Further to this, the advert says T&Cs apply, i have been to all the Terms and Conditions on the MTN website and there is nothing related to this deal, where are the T&Cs related to this voucher?? I am now highly frustrated with the service of this store management as i am yet to receive any form on contact from them!