Often unable to send/receive text messages

[DesperateTom]

My phone has been so wonderful for the past year, but in the last 3 weeks it has been my own personal .  I am often not able to send or receive text messages, I have no idea how to update my apps, the battery has gone from lasting two days to lasting just over 2 hours.  What the kind of update has messed up my wonderful phone?!  It also gets really hot, which I can't imagine is a good sign.

[Phy]

Boot on safe mode and see if you can send messages?

How to boot on safe mode
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

How to boot on safe mode on Lolipop
1. press and hold the power key
2. once you get the pop up menu 
3. press and hold "power off" 
4. Boot on safe mode should become available

[Phy]

If you can, repair the phone with Sony PC Companion
http://support.sonymobile.com/gb/tools/pc-companion/

[Christofer]

Hi @DesperateTom,

Have you had a look at what's using up your phone's battery, Settings > Power management > Power usage? Could you take a screenshot of both the diagram at the top as well as the list underneath it when your battery is down to 25% or less and post here?

Regarding your text messages, do you get any error message when you try to send a text message? Have you noticed if it mainly happens when you are in a certain area or does it appear to be completely random?