@c3user I am assuming it's an Automatic. This sounds like an issue with the selector, bad cable, bad adjustment or a bad solenoid in the valve body. For now look through this part of the SM [document|29047] that deals with identifying your transmission and how to adjust the selector etc. Let us know what you find out. You can always add pictures to your QUESTION in case you come across some oddity. Citroen for sale in Australia? That is pretty cool.