But does include monitors which a laptop has. Its the likelyhood of a damaged screen.
Not really sure what you're getting at?

to be specific it is desktop replacement 18.4'' screen so this is not really notebook not really desktop computer, large mix between
Regardless, the point i'm making is that you described it simply as 'comp' now given they don't exclude computers, they had no reason to suspect or method of determining that you actually had a notebook that would fall outside the terms of their insurance cover to start with.
If you had described it as a laptop then maybe you'd have a case that they shouldn't have sold you the cover and refused carriage but given your description again the onus is on you frankly.