I solved mine by changing the entire handle inside the car, because the part connected to the cable probably stretches, although you can't see it with the naked eye.
From the factory it holds very strong in three clicks, three "teeth", gear wheel, whatever you want to call it, when you pull the handbrake, that's how it was for me.
Many years ago, my wheel blocked, I immediately changed both cables because they were old. After the change, the handbrake was held high, which got on my nerves, tightening, nothing, changing the cable again, nothing, I took it to an authorized service center, nothing, I can't tighten the cable any more, everything else is fine. Some time later I bought another b6 just to take the dashboard and trow rest away from it. I took the handle of the handbrake of the donor and installed it myself in my car, the handbrake is tightened as if it left the factory.