sound from new Alto K10 Auto gear shift

I bought a new Suzuki Alto K10 Auto Gear Shift vehicle from Trichy ABT MARUTI. On the same day afterr delivery when we travel from the dealer's office to my home I noticed a sound from engine during decelaration. Immediately I reported to the executive for which i got the reply as this is normal case with this auto gear shift vehicles. But next day I handed over the car to their workshop and during the test drive the mechanic accepted that their is a sound from the engine.

4 days now till now i did not get the proper reply from the dealer what is the problem and when i'll get the car back despite my several visits and phone calls. 

They say the sound is from brake first then the sound is from drive shaft and then the sound is from gear box. they said theyy informed to maruti and waiting for them to check.

But never they say what is their action plan and when the vehicle will get repaired. I am fed up with their poor response and lethargic working style.

really i'm disappointed after paying overr 5 lakhs and i regret for purchasing the car.