A "loving, cheerful" 40-year-old woman died at her home in Dagenham after waiting an hour and 45 minutes for an ambulance. Victoria Yamphet's daughter Emmanuella called for an ambulance after becoming concerned about her mother, an asthmatic, who was suffering from crippling pains.
But by the time paramedics arrived, Mrs Yamphet had stopped breathing.
Emmanuella said her mother's body was then left on the floor for six hours after she died and the ambulance crew had left.
This was not a day ambulance staff were striking.
"She was a very loving, cheerful person, she would always give even if she doesn't have it - she'd always make sure you come first," Emmanuella told ITV News.
She added: "I would roughly say 2am - that's when she started really complaining, 'My belly, I can't my belly, my belly'. She still had the flu with her belly hurting and her rib hurting her."
Emmanuella said she was told there would be a six-to-10 minute wait for an ambulance. When it didn't come in that time, she called again.
She said: "She [the call operator] said 20 minutes. So I'm telling my mum '20 minutes they'll be here'. I call them back again, and the man said an hour."
A taxi was also booked by a paramedic to take Mrs Yamphet to hospital, but, according to Emmanuella, the cab arrived 15 minutes late - by which time the ambulance had arrived.
"Paramedics were able to get a heart rate - but it was too late," Emmanuelle said.
"My mum's a support worker and she always puts people first. And I feel like when it was her turn, she was neglected in a way.
"Timing-wise - I feel like they could've got there quicker.
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"If they did, it could've prevented all of this from happening - me grieving over my mum - everyone grieving over my mum.
"But obviously the NHS has been good to us, healthcare-wise, if we need help with anything. So I can't really complain."
Emmanuella said her mum's body was left on the floor for six hours after she died.
The London Ambulance Service said it was "deeply sorry for the delay in responding to Mrs Yamphet".
In a statement, LAS said: "We are investigating our response to this 999 call and the care provided.
"As part of this thorough review, we will contact Mrs Yamphet's family to understand the circumstances of this incident."
And that it will contact Mrs Yamphet's family as part of a thorough review of their response and care provided.
The cause of Mrs Yamphet's death is still unknown. Emmanuella has now launched a fundraising page to help give her mother a send-off she deserves. "I just did that because I felt like she's always been there for me so the least I can do is make small something."
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