I have Audi A3 1.6 2001 model with automatic gearbox and it just doesnt want to change gears, from 2nd to 3rd it changes only at 70km/h and it doesn't change from 3rd to 4th at all. Any advise?

check the linkages from gear stick to gearbox may be loose.

While just change ATF oil or CVT oil in transmission & old filter too. your car problem will be solve....

Check your ignition coils. One of mine was bad and when I replaced it, the shifting issue stopped.

it is slipping; you will need to rebuild or replace the transmission.

my 4k cant go to 2nd gear even you do adjustments.what is the problem?

two choices renew auto box ,fit a manual gearbox or scrap car and buy a newer vehicle ,Parts are a problem with these cars ,just not available

Release bearing problem.Change the clutch Assembly

You need to give the car a scan, preferably with VCDS (or VAS at a dealer). If limp mode is activating (lit up gear selections), then it will be storing codes.
The fact that it works to a degree could be good news, the gear box has likely not failed. Could be the F125 selector switch, which is a common fail at this age.

gears do not engage on audi a4

balls