2009 Audi A3 - Trans trouble

I have some trouble with the transmission on my Audi A3 2009 1,9

When shifting from 1 to 2 it makes a clicking sound. It also occurs when downshifting from 4 to 3 and 3 to 2. Its also very jerky when downshifting in low speed. Feels like it cant find the gears when I accelerate after breaking down.

When driving normally it lies on 1,5 revs, but if I drive with over 2 revs (<80km/h) over time it goes in “sport mode”. It also gets in “sport mode” if i accelerate a few times in at short time period, or driving uphill. When in “sport mode” it downshifts and holds at least 2 revs. If I force it in a higher gear the transmission gets jerky, feels like its clutching in and out in the same gear. The engine oil gets worm much faster than normal, and after parking the car it smells burnt. If I force it in a higher gear over a longer time, or not using the car in a few days it goes back to normal.

Talked with the local workshop, but they could not find any errors. The transmission was flushed 35000km ago, and the they did not find any reasons to do it again now.

Any suggestions what it could be, or what to do?

First off… 1.9 diesel engine? Or gas ? Quattro or no? Is this the 6 speed automatic trans with a manual shifting mode? Or the S tronic dual-clutch transmission? Trans was flushed 35K km ago but how many miles does it have total?

How do you know it is the engine oil and not the transmission oil??

It is 1,9 diesel, and not quattro. total km is 155.000.
I asume its the engine oil because that what it says in the driving computer. And yes, it is the 6 speed automatic trans with a manual shifting mode.