oven will not work because of timer?

hi people, if anyone can help i would be really grateful,
my new world gas cooker is playing up. the hob and grill are fine but the oven will only work when the timer is on, i know this is the case with most ovens however my timer is hit and miss. sometimes i can press the + and - buttons and on comes the oven but most times it will just display the word 'auto' down the left hand side the 00:00. i have tried unplugging from wall pressing all the buttons but the best way to put it is it has a mind of its own. once i can get the numbers to flash it will only let me press the + button once then just clicks back to same think. searched the entire net for 2 weeks be still no further forward.
many thanks.