Dave Hadley called 999 when his leg started bleeding at his home in Oldbury.
The 62-year-old, who did not know at the time he had cancer, says he was told by the operator it was not an emergency and to go and see his GP.
After more than 10 minutes of arguing, the grandfather-of-one called a doctor, who then arranged for an ambulance to collect him.
But by the time it arrived, Mr Hadley said it was almost an hour after the original call.
West Midlands Ambulance service today said it is investigating the claims.
Mr Hadley, who has liver and pancreas problems as well as diabetes, said: "I was trying to put on a brave face but I knew it was serious.
"I could not move.
"But the man on the phone did not seem to be bothered. All he could say was 'go to a doctor'."
Mr Hadley's wife Joanne, 50, left work to help her husband and also argued with the operator on the phone.
Describing the operator she said: "I have never encountered anything like it in my life."
Medics at Sandwell Hospital stopped the bleeding and Mr Hadley, a former sales representative, was seen by a consultant the following day, which was last Friday. He was diagnosed with cancer and is now waiting for scan results to decide the course of action.
He has made a formal complaint to the ambulance service and an investigation has been launched.
"This is not about me getting any compensation," said Mr Hadley, of St James Road. "It's about someone who was bleeding seriously who they wouldn't send an ambulance to."
Confirming the investigation today, West Midlands Ambulance Service spokesman John Hawker said: "We have received a formal complaint regarding our handling of a 999 call made in Oldbury on March 7.
"As a result, the trust is fully investigating the circumstances surrounding the call and our response to it.
"We will be in further contact with the patient and family directly to further discuss this case when the investigation is completed.
"It would be inappropriate to comment further whilst the investigation is on-going."