diane priestley was struggling to breathe and was starting to turn blue .
an investigation has found that an ambulance should have been given a response priority of eight minutes to reach the 57-year-old at her home in shildon , county durham .
instead , a longer 30 minute response time was assigned - which north east ambulance service -lrb- neas -rrb- still failed to meet - and the grandmother-of-nine died from a ruptured abdominal aortic aneurysm on arrival at darlington memorial hospital .
north east ambulance service admitted delay was initially due to the call-handler error .