Three years old' should not have happened if driven normally, on the other hand if driven continually over potholes,bouncing up and down kerbside,rallying on public roads, (or any other type of abuse) it will bust the shock seals and they will leak.
If above that does not apply to you! and you bought the car new, try the dealer see if he will replace the shock under good customer relations' if that fails write a letter to customer complaints (Vauxhall) telling them how disappointed you are with the the car.
Good luck! lots of complaints about the build quality of the Corsa.
Paul
October 2012