2014 Kia Other Knocking Noise at Take Off

Hi Guys!

I have a Kia Cadenza 2014 since April 2014. I have 2 issues :
- Since 4800 km, when coming to a stop, I can feel a one vibration exactly at 20 km/h. The service engineer explained that it is a jerky down shifting. He was talking about resetting values and fixed the problem. The same vibration comes back again and again after some hundred Kilometres. I service the car every 5000km. They fix the vibration in every service Today I'm 22000 km and the vibration is still coming back.

- Since 11000 km I have . ONLY After some drive and when the car is warm, I can hear a knocking like noise at take off below 30km/h. The noise is very clear during the first seconds of acceleration or when I keep driving at low speed forward and reverse. At neutral acceleration the engine sounds smooth and normal. When driving neutral at low speed the noise is not there. The frequency of the knocking get higher following the RPM. The noise is not metallic knocking, it sounds like a far away helicopter. The noise is there whether the AC is on or off. The same noise comes when gently accelerating while applying the brake.
In the service centre they say that the noise is normal !
I'm not expert, but after all the tests I have made, I believe that the problem is mechanical and in the Transmission. I suspect some loose or cracked part.

Please advise.
Thank you all.