The family at the centre of a diplomatic row after their son died in a car crash said they were “angry and frustrated” following a meeting with Foreign Secretary Dominic Raab.
Harry Dunn, 19, died in a crash with a Volvo in Northamptonshire on 27 August.
American diplomat’s wife Anne Sacoolas, suspected of driving the other vehicle, later left the UK to return to the US.
“To say we are disappointed with the outcome would be an understatement,” a spokesman said after the meeting.
He added: “We are frustrated. We are angry.”
Harry’s parents, Tim Dunn and Charlotte Charles, met Mr Raab in the hope he would urge the US to waive Ms Sacoolas’ diplomatic immunity.
The spokesman said the family were “extremely grateful” to have met Mr Raab, but needed some time “to gather our thoughts and compose ourselves” before commenting further.
Prime Minister Boris Johnson has urged the US to reconsider its decision to allow Ms Sacoolas immunity, while Mr Raab had already spoken to the US ambassador and Secretary of State Mike Pompeo.
Northamptonshire’s chief constable and its police and crime commissioner have also urged the Americans to waive Ms Sacoolas’s diplomatic immunity.
Harry Dunn died after his Kawasaki motorcycle was involved in a crash with a black Volvo XC90 in Croughton close to an RAF base.
He was taken to Radcliffe Hospital in Oxford where he died.
Northamptonshire Chief Constable Nick Adderley said “based on CCTV evidence”, officers knew that “a vehicle alighted from the RAF base at Croughton” and was “on the wrong side of the road”.
He said the suspect, Ms Sacoolas, had “engaged fully” following the crash and said “she had no plans to leave the country in the near future”.
On Tuesday, Harry’s parents said they would “go to Washington if we have to” to secure the return of Ms Sacoolas.