well I had this p8lite in Pk that has its wifi and bluetooth malfunctioning, tried all the tricks none of them worked, took it to the customer services they told me this model has defect in its hardware they are changing their motherboards so gave it to them and they returned it after a month with a new board and it worked and it was all done under warranty.
so I recon if you have the warranty, valid or not, u have to change the board or the wifi or bluetooth modules.