Richard Okorogheye's family has refused to accept an apology from the Met Police for failings in handling initial reports that he had disappeared.
Two weeks after he disappeared from west London's home, the body of the 19 year-old was found in Epping forest.
After he disappeared, the police watchdog concluded that officers had provided "unacceptable levels of service".
His mother said that Mr Okorogheye's apology to the Met was not accepted.
She stated that the Independent Office for Police Conduct (IOPC), which was investigating her, "has confirmed what my whole life knew - in my darkest time, I was fired by multiple Metropolitan Police officers at all levels of seniority and the disappearance of my son was not taken seriously."
She said: "It is a matter for deep regret that I cannot accept that, despite the Metropolitan Police and the IOPC concluding that the performance by three police officers, including an Inspector, and three call handlers was below the expected standard, nobody will face misconduct charges."
IOPC investigators reviewed complaints by Evidence Joel, Mr Okorogheye’s mother, about how she was treated during calls.
Last month's investigation concluded that officers had provided "an unacceptable level of service" to Evidence Joel, when she reported that her son was missing. The force should apologize.
Richard disappeared on 23 March 2013. His body was found in Epping Forest on 5 April.
The IOPC gathered evidence that police did not correctly record the medical condition of the teenager after being told he had sickle cells anemia.
The IOPC stated that this and other information should have reached the appropriate team sooner.
One of the findings was that Ms Joel was told, "If your son isn't found, how can you expect us to find him?"
She believed that racism was behind some of her treatment and that the police were too slow in classifying Richard as missing.
The IOPC investigation revealed that:
Bas Javid, Deputy Assistant Commissioner for the Met, stated that he would like to apologize for the distress caused due to the substandard service as highlighted by Independent Office for Police Conduct.
"It is evident that the service we provided in days following Richard's disappearance wasn't at a level the public would have expected. Richard was not classified as missing.
"His risk is not being upgraded sooner. The communications with his mom not being as informative, precise, and regrettably, an inappropriate and insensitive comment made by one our officers.
Follow BBC London on Facebook and Instagram. Send your story ideas to hellobbclondon@bbc.co.uk
