KIA Motors

Rear hatch on my 2014 sorento sxl goes up, then quickly comes down 3/4 of the way. This is very dangerous. I took it to sunset kia in venice florida and they told me the motor needs to be replace. The motor works fine, as the door goes right up. They wanted $1400 to fix this. I have done some research and Kia's own trouble shooting chart says its the gas struts. Would someone give me the correct answer and where I can get this fixed.