Paramedics were “devastated” to find a pensioner dead in her home almost four hours after she called an ambulance.
The 81-year-old woman rang 999 complaining of chest pains, according to a union.
Paramedics arrived hours later and had to break into her property in Clacton, Essex, but she had already died, the GMB said.
East of England Ambulance Service (EEAST) said crews arrived three hours and 45 minutes after the initial call.
Dave Powell, regional officer for GMB, said the paramedics were “emotional” after the incident on Tuesday.
He added: “They’re devastated because they’re not in the job to find people dead, they’re in the job to help people and keep them alive.
“It puts enormous strain and stress on people who are working really hard as it is.
“Three hours and 45 minutes is totally unacceptable for an elderly woman on her own with chest pains.
“Something has got to be done and the government has got to wake up to this crisis.”
EEAST previously said it has had to rely on taxis to take patients to hospital after struggling to cope with a surge in demand over the holiday period.
A statement on January 2 said the service received more than 4,100 calls on December 31 and around 4,800 on January 1.
“To put this into content, the trust’s average daily volume of calls is about 3,000 calls a day,” it added.
In another incident an 88-year-old woman died following a seven-hour wait for a bed.
Josephine Smalley spent five hours in an ambulance and another two hours on a trolley in a corridor at Queen Alexandra Hospital in Portsmouth.
She died on New Year’s Day, after having a heart attack and previously a stroke.
NHS England urged people to stock up on medicines, check on vulnerable or elderly neighbours and get the flu jab.