iPhone 6s with full bars and LTE, no data

I bought a new iPhone 6s about 2 months ago, I was with Freedom Mobile at the time and it wouldn't connect to the network at all, I brought it into a store and they said it was most likely because of Freedom as a carrier and because apple was not directly affiliated with them. I ended up getting a new plan with Koodo. Now, the phone can connect to LTE with full bars yet I can't send/receive texts nor can I use the data. Sometimes this conundrum subsides but only for a few minutes at a time. I don't believe it is a carrier issue as I have talked about this phenomenon and they say it is most likely the phone. Does anyone have any suggestions at how I can go about fixing this issue?