The BBC has found reports of numerous serious incidents.
Cases involve both waits for crews to reach patients, as well as delays when ambulances arrive at A&E but spend hours queuing outside, because the hospital is too overcrowded to accept the patient.
Margaret Root, 82, waited nearly six hours for an ambulance to come following a stroke, and she then waited for another three hours outside hospital.
When she was finally admitted, her family was told it was too late to give her the drugs needed to reverse the effects of the stroke.
