Useless Dell

I bought a Dell laptop but I have had nonstop problems with this laptop! It's not even a year old. The motherboard has been replaced twice and that's not the only part that has even replaced. I am a teacher and have struggled with this laptop throughout lockdown. I requested a new device and get told that it's not possible because of 'policy'. So is your policy selling dud laptops? Not happy at all about this. All my planning, marks, reports, etc are on this laptop that will not switch on! How am I supposed to work?