As per the title, the AFS or "Bend Function" has stopped working on my car. Got in it last night, and my headlights were just pointing to the ground so could barely see anything. I reset the code with Carista and started the car again and they moved left and right, up and down so I'm sure the motor is okay, but shortly after the warning came up again. Advice much appreciated.

probably you would have to replace afs module under your headlight !

What was the code you reset?

Could just be a broken level sensor linkage, or the wire going to the sensor or the sensor itself.

Should have good 5V feed and good earth going to the sensor.

Do a volt drop or scope the wires with reference voltage from battery terminals.

Check the output signal varies when moving the arm.

Dead short sensors will ground the 5v so also check the live and earth with the plug disconnected if you don’t have voltage when back probing, if you now have 5v, the sensor is dead most likely.

My car had a rusted ball joint on the link arm which had seized, the sensor was fine but TPS could only supply the linkage with a new sensor, I just swapped out the linkage and kept the new sensor for when the old one fails.

On the MK2 Superb, it's not uncommon for water ingress to cause corrosion on the AFS slave pins.

 

They are stuck on the underside of each headlight so not the easiest to get at.

If they started moving left right up down after erasing the code it suggests the self test is working, I would expect the motors to fail or not work in one axis with water ingress in the module. When it then does a sensor check it falls over if it doesn’t like the feedback loop.
Don’t just erase codes, work with them, it is trying to point you in the right direction.

Could be lots of things which is why you gather all the info before throwing parts at it.

MakIng sure you can prove the fault will keep your balance sheet healthy.