Hello!
I have similar issue with my phone. The signal is rubbish at times and I blame the device.I run a security business and I wish I never got this phone. It costed me a lot of unaccounted calls!
Along the signal, other things were going bad from the start; for example when I took photo with a flash, it looked like taken through the fog.
Another issues was receiving incoming calls! Sometimes the phone rings and sometimes it doesnt (just silent)!
Recently, the device failed to switch to headphone mode when I plug in headset; so I can forget listening to music; but I can imagine this is due to wear and tare (old age-got it brand new in June 2015).
I had it fixed twice by Carphone Warehouse; although they never really fixed it! I was advice at Carphone Warehouse to send it to Sony but I couldn't accept the longer waiting times. I just couldn't run business with a basic standby phone for such long period! I wish I did it now though!
