Vehicle problems

<p>Hellopeter my name is chrisjan duplesis.I bought a car on June 2015 model vw move up.on 2016 January t started to have noise in the gearbox I took the car for repairs more than two twice but still no solution.then this month on the 2nd it reflected an epc light fault in a engine then I reported the car.they took the car to pta wonderboom vw.they diagnosed the car now they telling me that they won't cover by the warranty cuz I've inserted a subhoover in a car it caused distortion now they saying I must pop up 16000 so that they could fix the car for me.BT my car still under warranty please help me guys</p>