I send my Phone to customer care last wednesday. I received the phone today. They told me that they had changed the touch panel of my phone. I ask them more than twice is it true or not. They told me yes they changed it. But changing the touch panel doesn't solve the problem. I show them the problem again. They agree with me and depressed me by saying that they can't do anything right now. They suggested me to visit the care center later.
Anyway I think the problem is still software rather than hardware. Can you remember before the update there wasn't any touch problem during charge? After the update the touch become horrible during charge. Also the touch improved in such situation I think.
Lets wait for MS decision about the device since they already started invesitng about the problem. :S