adverted goods ate not in stock at all branches

On attempt to purchase a prepaid mobile phone from an Mtn store as per the advertised good in the August addition I was told there was no stock by the riverside branch. On contacting all the stores in Durban none of them had stock and every person I dealt with took my details but never got back to me . They have pathetic customer service and 2 weeks into the month none of the stored have received stock of the phone I am looking for. Im not sure if its just false advertising in attempt for customers to choose other items from the catelogue or just terrible customer service