My hygena oven wont turn off!?

I have just purchased a hygena yroltic pelectric oven. I have just used it for the first time,when i turned both the controls to 0, the cooker reamined on! I think it is something to do with a timer, i have pressed all the buttons, turned the appliance off at the mains,but as soon as i switch it back on the cooker comes back on. The instruction manual is no help, neither is HYGENA. If it continues i will be returning the item and purchase another cooker which is not hygena!! Please help