Doors wont lock HELP Please

hi, i have a 300tdi disco, its an R reg, (with only 40k (genuine)) i currently hate it, but maybe you can help.

the doors will not stay locked, i press the button, they go down, then within seconds they all pop up again, its the drivers door that is the problem, i have locked all the others from the inside and not bothered with even trying the drivers door.

the key goes in and turns but nothing happens, and when i try and push the thingy down it just comes up again, (and unlocks all the other doors)

a few weeks ago we took the door card off and lubricated evrything with wd40 and oil, and it was okay for a while, but has now started doing it again at the most inconvinient moments,

i assume i am going to have to buy some bits, could somebody give me an idiots guide to doing it. (i'm a very hands on female, but an idiots guide is still very useful) and an accurate description of what i need to buy.

also at some point in the cars life some moron has dissconnected the alarm, the lights all flash but there is no noise, any ideas please (the immobiliser works)

looking forward to all you bright ideas, and any volunteers to do it for me!! i'm near poole! (no money but would pay you with hugs!)

dont think you'll need to buy any bits..

just needs a bit of adjustment on the solenoid that makes the pin go up and down.

If i remember correctly, the pin is connected to a hook and you can adjust the lenght of that hook...

what I reckon is happening is the hook is too long, so when it pulls the pin down (to lock the doors), it goes back up and its just halfway on the trigger between open and close...