My GF has one she got on contract & every time she doesn't pay the bill the phone overheats to the point were its crazy hot to the touch.
I've discovered that turning off the packet data stops the over heat & that the problem is caused by the phone company,ie.when she gets her phone bill paid her calls work straight away but the 3g signal doesn't so the phone starts its rapid heating process.
When she rings them to say hey your overheating my phone again they say the usual bull shit story & tells her to turn off her phone for 10mins & then turn it back on & it should be fixed within 10-20 hours,well the second she gets of the phone the signal is back & the phone stops its overheating process.
I've been trying to get her to video & document it as the phone is obviously sending constant packets to the 3g network & when they get blocked bad shit happens.