In reply to Green Porridge:
I've had a similar problem on my Golf. It is, as suggested above, the hazard switch (which contains the flasher relay), cheap to replace, easy to fit yourself. It is a push-fit, with metal tangs either side, and plugged connector at the back.
BTW - the front of the switch snaps off, to give you better access to depress the metal tangs to each side.
Post edited at 21:44