1998 Opel Corsa Ignition Switch or Barrel and key

Electrical problem
1998 Opel Corsa

I started my Corsa and nothing happened. The lights just kepts for the battery, fuel and other lights in that category just stayed on. Turned the key to switch of but nothing happened. Lights stayed on. Had to disconnect battery for it to turn off. Found out that the pin from the barrel and key that fits into the ignition switch broke off. Can this be bought seperate or do I need to replace the entire barrel and key. But this new key will then not fit on my doors. Have to use two sets of keys than.