Hello andrewbarker82,
Sorry to hear you are having that issue. I would first like to state a few things. First, do you live in an area with low cell signal? Or is this an all around issue no matter where you are? Second, where did you take your phone to be fixed. I'm not saying the repair shop did this, but when replacing the screen, they may have damaged the cellular antenna, weakening or disrupting cell signal, which would hold them liable, but that is a ''rare'' occurrence. Lastly, my most recommended option, is to file a claim with Razer as the phone should still have the manufacturers warranty and this could be issue with the phone that only affected it later, similar to the iPhone 6 "Touch Disease" issue.
Hope this helps!