Ford Focus used max defrost once and windscreen has cracked

That car should have heated quick clear screen .Myself , family and many friends have used this over many years on different Ford cars from Kuga , Focus and Fiesta models and never had any problems . One of the best features on the car especially in winter . I have three family members who have this on current cars and really appreciated it through the recent cold spell . I have never heard of anyone or had any in my workshop / bodyshop with a cracked screen caused by this .