Wattbike Atom pedals seized up

Hi All,
I jumped on my Atom last week to find the pedals have almost totally seized. I registered 600W just trying to turn them!
The bike was working fine two days prior to this.
Nothing I do reduces the stiffness - quick ride in gear 1 or turning the Atom off.
Has anyone had this problem before. I got in touch with Wattbike but no response yet (5 days)