i have a gas cooker ?

Part or all of the unlit side of the oven burner is choked.It may be possible for you to fix this yourself.Turn off any power to the cooker,get a torch and stick your head in the oven right to the back(make sure the oven is cold and unlit).If you can see the burner,see if any of the small holes are choked,if they are,using a soft brush(small paintbrush)try and clear it,also try using a small rubber tube to blow any choke clear.
If that doesn`t work you need to get a Corgi Engineer in to remove the oven burner and clean/or replace it.

Gasman
August 2008