What to do re cracked Schott Seran 4 zone hob?

We had our kitchen reburbished eight years ago (although it seems have that time) which included installing a Schott Ceran 4 zone hob. Two nights ago, about an hour after dinner, there was a loud "cracking" noise from the kitchen which in the morning turned out to be the hob glass splitting in two, the split going from front to back. It was bizarre. The hob was "off" and there were no saucepans on the unit. Has anyone had the same experience and what action did you take? Thanks.