DTEK 60 Network Issues

I'm wondering if anyone else has similar issues and what the best route is to get this repaired.

Basically, I've had my phone for about 6 mths now purchased from Shop BlackBerry Canada. I've always had some network issues but always seems to be when I'm at home. Due to having a work phone though, that is my primary contact and usually just use this phone as a glorified tablet when I'm at home on wi-fi the network issues at home haven't proven to be a big headache for me but more a mild inconvenience.

Even when showing 3/5 bars and LTE connected, I can't make or receive calls with this phone although texting seems to work. I have tried switching the sim as originally I thought that was the issue but that was to no avail. I've also tried swapping Sims with my work phone but continue to have issues with this phone regardless of the sim and when my sim from this phone is in my other phone, calls to and from that number all of a sudden work fine.

Any ideas on the best route to get a replacement? I'm wishing I would have purchased from Amazon as I've heard they are very easy to deal with however I can't seem to find anything on dealing with shop blackberry.