Faulty car sold to me and will not exchange!

I traded in my car and bought a vw polo gp 1.2 TSI highline from Vw Acardia on Monday 23rd November 2015. <br> Problems began same night after i took delivery of the vehicle where the car had strange loud noises<br> coming from the engine. I took the car back on the 24th November 2015 and it had been repaired and <br> i got it back on the 27th. I called the dealership on the 30th November 2015 as the aircon too was not working.<br> Yesterday 9th December 2015 there are new noises coming from the engine.<br> The dealership made me wait for 3 hours as nobody is willing to assist. I was told that they would<br> check what the problem is and revert back to me. Now i am stranded without a vehicle but paying installments<br> for something that is more broken than working. I regret trading in my perfectly working car for this *******!!!<br> <br> Why can this car not be replaced with a working vehicle as i only have it for 3 weeks???