Hey guys the missus rear drivers door isnt locking in her nl fairlane and when you pull the handle from the outside it unlocks the whole car, any one know what the problem could be??

can be latch assembly and or actuator -
check that child lock is not jamming/half on-
remove door trim and lubricate latch assembly (WD40 Etc.)
disconnect link to actuator- roll lock with a screwdriver and lock with link from actuator - test for latch assembly still releasing(it may be necessary to release with a screwdriver) when you pull handle from outside if it does replace -
operate actuator by hand and remote to check if holding in position when operated