Works for Lupo 3L conversion

Hello together, someone here from the forum knows a workshop in NRW, which can make the conversion of a 3l Lupos? To be converted, the circuit, i.e. from hydraulic to manual. I am also unsure if the effort is worth it. I got a 3L Lupo with 327,000 Km, which needs the gearbox basic adjustment every 4-6 weeks. I can now not say why this is so and the workshops actually have no explanation for this, but before I enter the path of suffering with a new Gansteller, hydraulic tank etc., I could just have the conversion done and then would have some rest. How high would the costs for a conversion in a workshop be? What total running performance can be expected? Is there anyone who could reach more than 400,000 Km with a Lupo 3L? I would like to thank you now for every assessment/answer.