How can i fix the brake lights on my 2003 Vauxhall Astra sxi?

are the correct bulbs fitted in rear bulb holders,there may be a wrong bulb in tail light [a single filament double contact bulb or a single filament single contact bulb]which is shorting to stop lights. it should possibly be a 21/5w stop and tail bulb that you need ,this has 2 filaments and double contacts, pins are offset to ensure that bulb is fitted correctly!

k
November 2009