Diesel mechanical noise problem

[80386i]

Hi everyone-

I have a strange noise from the passenger side when the car is at idle or is moving without the gas pedal is not being pressed. It only lasts for 5-20 seconds at each incident. The problem is that this occurs at a random time mostly when I start the engine in the morning (not always). I was able to record some of these noise and I attach here.

Guys at dealership did hear the noise but they were not able to replicate it and now they are basically telling me to take the car back.

Could anyone have any clue? Also, how should I deal with this response from the service?

Thanks!