MTN Samsung S9 voucher ****

I upgraded to the Samsung Galaxy S9 on Saturday 25 August, which MTN advertises comes with a R500 voucher which can be redeemed against the purchase of any Samsung branded product. This was great as I planned on purchasing a wireless charger, so I would use the voucher towards this. When receiving the phone the consultant informed me that they did not have any wireless chargers in stock and they could only offer me a cover. I did not need a cover as the S9 comes with a cover in the box. After visiting a number of MTN stores I was told that no stores have stock of the wireless charger and would need to buy a cover if I didn't want to lose the voucher which expires at the end of the month. I have therefore been forced to purchase a cover I do not need, when one of the reasons for me choosing the S9 was the fact that I would receive a voucher to use against a wireless charger. I have not opened the cover as I would like to return the cover in exchange for a wireless charger. I look forward to MTNs response.