It doesn't sound like rubbish to me.
I feel for you but if there were a small crack on the screen when you bought it, any resultant damage would been likely to have shown up shortly after.
Most likely, the crack has been caused by an unrecorded dunt while in your possession. Sad but difficult to prove that it was not.
Screen damage and broken Charging Ports must be the two most common forms of laptop damage there are and so easy to miss their actual occurance that many people think that they must be a manufacturing fault.