Sim card error and other problems with new phone?

A

AC Question

I have a Samsung Galaxy S5 and switched carriers from Verizon to Virgin Mobile in September 2015. I immediately I got a notification that says "SIM card is not from Verizon". I also cannot access my voicemail because it dials Verizon instead of Virgin when I try to call it, and I get an automated message saying "The call cannot be completed as dialled". My last problem is that I can't send or receive pictures, although my mom can and she has the same phone and plan as I do.
I've done a little bit of research and found out that Verizon doesn't lock its phones, so I know that that's not the issue. I have tried calling customer support, but they tell me to go to the Virgin Mobile store, and when I go there they tell me to contact support. A few have tried and failed to troubleshoot it.
I don't want to have to drop $600 on a new phone because I just got this one before I switched providers.