just had the same thing with my 05 citroen bongo,light on constantly. took it to my mate with who has electrical testing kit and he diagnosed the alty was not charging,it also had a unusual noise comming from the timming belt + alty area so i was a bit worried it could be serious,as it was just the alty we whipped it off and took it to a starter alty specialist by us who recons them cheep,25 quid later i was well happy the van drives mint.

theres more than 1 alty for a bongo and i was quoted 45+vat for a second hand one and i would of needed to compare them first which would of meant a 20 mile round trip to a van breakers.

theres bound to be a company like that in sheff matey.