passenger side door issue !

Howdy,

This is bugging me ! anyone got a solution or is it another garage job ! is this the new 'wiper arm' 'air bag warning light' 'door loose on hindges' jinxed mk2 punto things !!!!

my passenger side door handle is sticking , if i unlock my car with either the remote or manually and try to open the passenger side door it locks all the doors on the car when you pull the handle ?

its driving my girlfriend mad !
and on a negative side its caused some problems example - a few months ago i stopped to sign in at a security lodge (leaving my engine running and shuting the door) and asked one of my staff if they wanted a lift to the next building , she said yes and before i could open my door she had pulled the passenger side handle and it locked my car with the engine running and keys in the ignition ! funny now but a nightmare at the time.

anyway i've tried wd40 so far !

fiat punto 1.9jtd elx 2000 3dr