My old man's lock barrels have packed up in both front doors. Now I need to get them replaced, but don't want an entire lock set, and don't want to use secondhand ones as there is no guarantee they don't pack up as well 3 months down the line. I am not replacing the ignition barrel, nor the boot, only the front doors. I know this will involve carrying two keys, one for ignition and boot, and the other for the new door locks. Trouble is I can only find new barrels for manual locking, and this one is central locking! I believe I need the command ring???? Where from do I get these?