Overheating Issues with Xperia SP

[sam22]

I'm using xperia SP. After updating the 11MB update(12.1.A.1.201) I'm facing overheating issues.The phone gets heated up very quickly. After 3min whatsapp use and 3min of web browsing. Earlier than this update it ran fine but its bad. Please tell me what I should do.

[thamjid]

Keeping idle is a funny solution. We bought this phone to use. I did hard reset and i.have latest software. Nothing helps