Problem with defective automatic transmission!

Hello, Our vehicle is a Pössl Campster based on a Citroën Jumpy Spacetourer. It is the version 2L Blue HDI 180 hp with the automatic transmission ETA8. Our vehicle was approved in December 2020 and has about 147,000 km. The problem with our automatic transmission began with symptoms where the 4th and 6th gears were skipped. A first diagnosis indicated a problem with the solenoid valves for the 4th and 6th gears (error memory P0729 and P0734). our workshop was saying that this could probably be fixed by a software update. During the examination by the workshop and according to all methods for diagnosing the problem, the transmission oil was finally drained and determined that it smelled burned. The final result of the diagnosis: The automatic transmission is defective and must be replaced. The workshop offered us to contact Citroën to have the damage repaired by culant. A few days later shared The workshop with us, Citroën gave us a negative answer because of the high mileage! What surprises us is that no oil sample was sent to Citroen for analysis of the contents! We have also been informed that there is currently no replacement automatic transmission available. At present we have an estimate for the replacement of the automatic transmission in the amount of 11,000 €! There are different opinions about the life of an automatic transmission and its maintenance. At Citroën it seems that it is The question is, what Citroën means by “life long” in terms of kilometers and duration? I would like to know if anyone has already had this experience and how it went out. Thank you for your efforts !!!