Cant make calls on samsung s6 edge plus

[AC Question]

I got a S6 edge plus that was from verision but was unlocked, I have switched carriers to AT&T and can text, receive calls, and use 4G LTE data but cant make any calls. When i go to call someone it says my "balance is to low"or "no SIM or SIM error". When i go to check balance by calling *755 it takes me to the My Verision app and doesn't load up. Is there anyway that I can somehow delete Verision from my phone, or am I going to have to factory reset the phone?