4 LAPTOPs switches off; not one - all four

Hi we have 4 of the laptops bought from Dionwired. They either stay on forever, or switch off while you are taking a break in typing. The on-site warranty team had mine for 10 days and say it never switched ff. Should I now bring all 4 in? There is a fault with this software. I have 30 months of warranty left, but dont want the machine and feel awful to try and sell it. The technicians say they are not allowed to change this faulty software.