Why am I not receiving Messages on my LG Apex?

I recently switched my phone to the LG Apex. My carier is US Cellular. Since I got my new phone I do not recieve messages from some people, not all. It is very frustrating. They recieve messages from me though. I went to my US Cellular and they erased all my data and stuff to make it work. It did nothing. This is very frustrating and I dont know what to do now. I also get these weird Brew messages that I do not know what they're for. Please help me:(