You will have to follow the wires to the 3 connectors (grey,black,brown ) which are under the steering column. Seperate them after first disconnecting the battery. Gently pull the ignition barrel out from the column and at same time you will need to push the wires up through the hole under the column.
The three sets of wires are of differing lengths, so when the shortest one reaches the hole under the column, you will then need to push the connector block through the hole, pull on the barrel a bit more, then you should be able to pull the two wires and connector out, which then makes it easier for the remaining two sets of wires to come out. These will need to be removed in the same way. On mine the black was the shortest followed by brown then grey. Once the barrel and wires are out, you will see a small torx screw underneath the barrel, unscrew it and gently pull the barrel and the white plastic part which has the wires attached to it apart about an inch.You should then be able to lift the white plastic part away from the barrel.
On the end of the plastic part you should see numbers 1 to 12 and a rotary part with a grooved bit in the shape of (Y) Insert a screwdriver and you should be able to rotate this from 1 to 9 easily. (You should hear it click three times) I suspect it will be jammed. On mine it had overheated for what ever reason, and fused all the internal components together. Hope there is a scrapyard close to you, because you wont be able to buy the plastic part and wires from Citreon without buying a complete ignition barrel. I have picked up the plastic part and wires from my local scrapyard for a fiver. It sounds a difficult job, but I have changed this part three times now, and it now takes me about half an hour. Good luck.