hello..i just bought this phone for a week..but i have one issue regarding to its screen

i bought this phone online so i got it with screen protector already attached on the screen.

i found that its quite unresponsive especially when to swipe out the wallpaper to unlock the screen..

always dropping calls coz by that problem..

so my question:

is this prob caused by the cheap screen protector or by hardware/firmware itself?

thkz for helping :/