Battery Life Significantly Shortened After Repair

[Colstong]

So about a month ago my phone overheated, turned off and wouldn't start or charge. I sent it to Sony for repairs and they sent it back apparently fixed. It did turn on and charge but since then I've noticed a severe drop in battery life as well as a few issues with the network connectivity. I contacted Sony again and they replaced the battery and apparently the phone passed all the tests but I noticed no change in the battery life. There's a screenshot of the battery usage graph below, WIFI, Bluetooth, Data and GPS were all off and the display was off for the duration. The phone lasts about 12 hours on standby and drops rapidly if the phone is awake. Does anyone know what I should do about this, I don't really want to contact Sony again but I don't see what else I can do. Do you think this battery life is unreasonable?

[Samuel1]

Well, it still might be the battery that's faulty. What apps have you installed? Any system changing apps like power savers/task killers/antivirus etc? These take a lot of battery.

Also, how is the network coverage where you live? If the coverage is weak your phone might need to switch between GSM/3G and that is very power consuming.