Someone changed my phone carrier

I have an iphone 5c that I have owned for about one month. I subscribe to Straight Talk wireless carrier. This afternoon, I activated another phone through ST (not an iphone) and shortly after that I noticed that I had no cellular data package on my iphone. Prior to this incident, the carrier name in the left upper corner of the phone would read :TFW LTE". Now is says "HOME 4G". Even with this I cannot access any internet, email or anything other than a phone call. I called ST on my iphone and was told to call from another phone. After connecting again with ST, I noticed in settings that my carrier is now AT&T. I told the CSR at ST that someone had to have done something on their end to create this error. After about an hour with them, they were perplexed. They wanted me to factory reset my phone right then, but I said that I needed to backup everything to my itunes account first. We tried resetting the network settings, but that did not work. Any suggestions?

UPDATE: After plugging into itunes it updated and now the phone shows TFW LTE. Have no idea why this happened in the first place. Anyone else ever had this type of situation?