On my 2003 vw Passat when I take my ignition key out the radio stays on and the central locking will not work but if I put the end of the key just inside the lock and wriggle it there is a click and and the radio goes off and the immobiliser kicks in can you just buy the black part on the ignition and is it an easy fix or will I have to get a full ignition?

the security system is more than likely programmed to auto lock when ignition key removed and when door closed after you exit the car if you have a owners manual it should explain how to able/disable that function using the dash functions controls if that does not work you have a security system fault and you need to visit a vw garage good luck

Sounds like you either need another lock cylinder for your ignition or your central electronics module needs to be readapted in the CPU. When you insert your key back in and turn to the start position does your car start? How about when you remove the key now? If it won't start now, or if the ignition lock cylinder doesn't move freely, then you probably need a lock cylinder. Adapting your central electronics involves finding someone with a VAG COM cable and laptop, with the information provided in the wiki at VAG COMs website. For instructions on replacing your ignition look in the forums on VWvortex.com

Those VW key fobs have a tendancy to fail...a replacement from your Dealer may be necessary.

Is this a factory radio or aftermarket. is this the radio vw put in or is this a radio you put in,

Programming
When
Key added or replaced. System malfunction.
How -

98MY
Keys can only be programmed using diagnostic equipment.
NOTE: A maximum of 4 keys can be programmed.
How - 99MY

Switch ignition ON. Insert key to be programmed into driver's door lock. Lock vehicle manually. Press lock or unlock button. Wait at least 1 second. Press lock or unlock button again. Vehicle horn sounds to indicate correct programming. Keys can also be programmed using diagnostic equipment
Above is how to re-programme a replacement key/remote

try the battery

check starter motor

check all the fuses on the fuse panel (located on the end of the dashboard). Behind the plastic door, drivers side. Then see if all the windows will go up and down; locking and unlocking the door with the key in the door lock. You have to hold the key in the unlock position to make this option work.

i had the same problem and i fixed it yesterday. you will have to strip the door down and remove the central locking unit. expect about a 3-4 hour job (at least).
check this site out taligentx.com: Passat - Door Lock Mechanism Repair. its **** hot.
mine had rotted inside, i tried to resolder it but it was to corroded i ended up soldering wires to the circuit board and splicing the into the loom on the door.(bit of a botch but it works great)
you can get a second hand unit if you cant fix it for about £50/£60 or pay a garage about £300 to do it.
believe me it was worth about 4hrs and gettin peed off to save the money.
hope this helps.
emptyed : )