The Argentinian ambassador has accelerated her argument with the BBC over a controversial Top Gear special filmed in the country.
Alicia Castro, the country's ambassador to the UK, has written to BBC Trust chairman Rona Fairhead expressing her "discontent" after a meeting with the corporation's director of television Danny Cohen.
The motoring show's crew fled Argentina after trouble erupted when it emerged they were using a Porsche with the registration number H982 FKL, which some people suggested could refer to the Falklands conflict of 1982.
Top Gear executive producer Andy Wilman has denied the number plate was a "stunt" and presenter Jeremy Clarkson said he was "shocked" when someone pointed out the link between the number plate and the war, days into filming.
Ms Castro subsequently met Mr Cohen, but he refused her demand for a public apology and said the BBC would screen the show.
In her letter to Ms Fairhead, she said: "We believe Mr Cohen's rejection is perfunctory and he has not investigated the issues we raised in any depth."
Ms Castro said she was issuing "a formal request" to the Trust to examine what she said was "the failure of the director of television to handle properly our complaint".
She also said she believed "Mr Clarkson's behaviour fell well below BBC's editorial values and standards".
A Trust spokeswoman said: "We have received the letter and will be responding in due course."
Ms Castro is not the first diplomat to be upset by the long-running motoring show.
In 2011, the BBC had to apologise to the Mexican ambassador over comments made by Clarkson and co-hosts James May and Richard Hammond.
May described Mexican food as ''like sick with cheese on it'' and Clarkson predicted they would not get any complaints about the show because ''at the Mexican embassy, the ambassador is going to be sitting there with a remote control like this (snores). They won't complain, it's fine".
Mexican ambassador Eduardo Medina-Mora Icaza wrote to the corporation to complain about the ''outrageous, vulgar and inexcusable insults'' and the BBC had to say sorry.