Suzanne Webb MP said the force was “piling injustice on injustice” on the family of Mr Passey, who was stabbed to death in a Stourbridge nightclub in August 2017.
She said the family had been promised a review but had not been given any confirmation it would take place.
Family friend Jason Connon said: "This is a long-running saga and it has got to the point now where we have lost all trust and confidence in West Midlands Police and the investigation that was carried out."
Mr Connon said the family had requested an independent review into the case by another police force.
Stourbridge MP Mrs Webb said: “Despite assurances to myself and to Ryan’s family nearly a month ago, West Midlands Police have not kept their promise to announce they will review the case.
“This is incredibly disappointing. It is piling injustice on injustice for this brave family who have spent years now trying to get the authorities to look again at who is responsible for Ryan’s death.
“All they have is a vague promise a review is coming. No-one even knows what shape it will take or if it will be undertaken by another force.”
She said that a review of the original investigation needed to be “independent and to start right now, especially when it has been promised”.
The MP added: “I do accept the police have a difficult job but no stone should be left unturned if we are to find justice for Ryan and closure for his loved ones and friends.
“It’s now been more than four years since Ryan’s death. I know his family will not rest until answers are found and in this they have my full support.”
Mr Passey, aged 24 from Quarry Bank, died after being stabbed following a fight in the former Chicago’s nightclub.
Kobe Murray admitted stabbing him but walked free after a jury acquitted him of murder.
Mr Passey’s family have been campaigning for justice ever since, and have hired a private investigator in the hope that fresh evidence can be unearthed that leads to a retrial.
In August his family launched a civil action against the man who was cleared of murdering him.
The hearing is due to conclude next week.
West Midlands Police have been approached for a comment.