14z-multiple system/power failures

I've had a dell technician out 3 times in the last week to replace a touchpad issue with jumping cursor- they replaced the mother board also.  then the display went bad. tech came out and replaced mother board but the new MB would not power on so he put the old one back in. said it must have been a loose connection to the screen. next day, system would not power on.  came out today for the 3rd time and replaced MD, power charge connector, new adaptor and who knows what else.  working fine until the laptop just shut off. can't power on- can't do anything.  i've been asking to get this lemon replaced. send me a new 14z and i'll put my old hard drive in and be good to go.  but they won't do it.  it has to be repaired.  take care of this problem and give me a new computer. stand up for your products.  it is a 6 month old lemon. oh, and in trying to repair it the first two times, they fried the cable to the webcam also which today's tech pointed out to me.  i am stunned by dell's response.