Security Code Doesn't work

[LanceA1972]

I have a new Iphone 6 and have installed Verizon messages to the phone.  It has me type in the number I want to receive texts on and then says it will text me a security code.  It takes around 3 hours for security code to get to my phone and then when I type it in the code doesn't work.  I have talked with tech support and they think I need a new phone.  I do see others are having similar issues so I'm thinking it is the app not the phone.  I have gone through a factory reset of phone and codes still don't work and still takes 3 hours to receive the text.  Any help would be great.