Samsung Galaxy j3 orbit has many issues

I have a Samsung Galaxy j-3 orbit that is on the straight talk Network. Ever since I have bought it four days ago it will not connect to 4G LTE it won’t let me get on the internet even with the 3-g and also people tell me that they have called me and my phone does not ring and also I tried to make calls and it will not make any. I have contacted straight talk to get them to send me out a box so I can return it but they’re telling me that they checked out my phone information and for some whatever reason it is not eligible for a replacement, even though it is only 4 days old. I have talk with tech support and have done that APN make sure everything is corrected on there and it is I have done a factory reset and still nothing. is there anything that you might think that you could help me out with to be able to get it to work? I have had other straight talk phones and have never had this issue or problem, any information that you could think of will be of great help. I am at a loss and straight talk will not help me. thank you for your time and I hope to hear back from you as soon as possible.