How does a new computer crash

I bought my computer in December 2014. In the first few months one of the USB ports broke and end July 2015 I without warning got a black screen when the machine was started up with a message that windows was downloading files - this took 18 hours and then it would start all over again. I did not request any downloads or updates so not sure why the machine suddenly did this. I could not get passed this screen. I have had plenty of other computers (mostly Dell) and have never had my computer crash on me. I have been told the hard drive was completely unreadable and this was replaced. When I enquired about fixing the USB port at Ensure IT Services I was told it would be for my own account. One of the technicians, John told me the tiny part is soldered on. My question is why should I pay for something that has been poorly assembled and comes adrift in the first few months of use?