Cellphone purchased from pep stores defective

on 23/10/2017 I purchased a hurricane groove dual sim, upon returning to my offices I put in the sim cards but saw that it wasnt reading the sim cards, it just said emergency calls only. I called the store on 24/10/2017 and I enquired if I can swop the phone for something else or get a refund but they refused. someone needs to help me because the phone is constantly going to emergency calls only and because of this I cant make or receive calls. MTN is the service provider for this mobile and they should live up to the level of standard that they give all their customers. the phone is only 2 days old yet I'm already having problems. are these the type of devices that MTN wishes their customers to use. the mobile is defective so I must continue to buy more mobiles because the store refuses to swop the item for something else or refund my money. I find the fact that I cant get to swop or refund for this defective item abhorrent. I want an answer to this dilemma before close of business today because I need the cellphone to work, it shouldn't just lie in my bag taking up space. the preferable option to me would be to get a refund because I'm not sure that the next replacement I get will work or do the same thing.