Bush IDLCD37TV07HD: How do I select 16:9 Picture format as default?

My Bush 37" LCD TV is fed by Sky TV Dish, has no teresstrial aerial input. Despite the skyBox picture menu settings being at 16:9, the TV often defaults to a 4:3 auto picture format e.g. not widescreen. I can see nothing in the manual or on screen menu to select 16:9 as default on the TV. Any ideas how I do this or, is there a contact for Bush Customer services - they seem elusive!

Pawl
December 2009