Vauxhall Astra 1.6, 8v auto (odometer data disappearance)?

The records of the milage on my Vauxhall Astra says "------" instead of (eg. 045623 ). The upper number still counts but the milage driven has disappeared. Can anyone help me out here?
Vauxhall Astra 1.6, 8v auto (odometer data disappearance)?
sadly the clocks have failed and will be needeing replaced.