Disappointed

We bought 2 Samsung A03 from Akermans Alberton City the sales lady Philile Mthembu said that those are very good phones. I am very disappointed as the phones keep saying IME with the number and says the following Your SIM card cannot be detected or is from a service provider that isn't supported. Try using a active MTN SIM card. This is the same sim card the sales lady Philile Mthembu put in the phone. I ask to speak to the manager Thabo Tlala who said phone head office there is nothing he can do unless we book the phone in for repairs and this will take 6 weeks. Why book the phone in if its not even a month old? I am not happy with the customer service that I got. Can not use the phones why????