LG4 Curve

I Upgraded my phone in September 2015 soon after this people started complaining they dont get hold of me on the phone, the handset is always on and shows 3 to 4bar network but they dont get hold of me, I went to the network operator and they changed the sim card but still the same problem, I send LG a email stating this problem, in december 2015 and still no one responded, I dont thing LG G4 is a great phone anymore if they only emailed or phoned to confirm but everything is only money money money, if they sold the handset why bother they got their share<br> <br> I just want to find out if its a software issue ot hardware