POOR MAINTENANCE OF DEVICE AND SYSTEM CRASH

My device was poorly repaired while it was in warranty, company replaced hardware which didnt fix the issue. They didnt try to find root cause and never solved the problem, Now device has crashed and i think its because of planned obsolescence , even operating system microsoft is not allowing complete back up of data as it doesnt copy all files which after crash could lead to data loss. Who should be held accountable for data loss and how do i proceed further .