Reason of overheating are plenty. Forgot to top up coolant, engine cooling fan is not working, AC cooling fan is not working, thermostat failure, clogged radiator, burst coolant hose pipe etc....! Apart from human negligence of not toping up the coolant at regular interval you can blame everything else on peugeot service center if they have not changed or serviced any of the above stuff in time, that caused the engine overheat and permanent failure.