Whirlpool
Cracked hob blamed on 7mm x 2mm smaller dimension

I have been informed that the guarantee is not being applied in resolving the case as it has been stated :
- The hob AKT821/LX aperture size is smaller than the stated size of :
o Whirlpool breath : 492 mm. Actual breath 485 mm DIFFERENCE : 7 mm to one side OR 3.5 mm centred on each side
o Whirlpool width : 562 mm. Actual width 560 mm DIFFERENCE : 2 mm to one side OR 1 mm centred on each side
I would like to understand the allowable tolerance on the dimensions quoted? There is significant space between the back plate of the hob and the edge of the aperture on the width and breath- the unit fits in well.
The decision to cancel the warranty is based on 1 mm centred and 3, 5 mm centred under cut on the width and breath? Please state the tolerance and how to cut Granite to a 1-3.5mm tollerance inorder to meet your exacting dimensions-CASE S 33 4024 -
This is the 2nd failure in as many days as getting the new unit (3-5 days). Your call center was suprised to be told that the installer was called back the next day due to a loud "bang" from what he assessed to be a defective plate. My maid noted the crack a day later? Co-incidence?
Disappointing product and service!!