A pledge by the new BBC director general, George Entwistle, to put more older women on screen has suffered a blow with the former Countryfile presenter Miriam O'Reilly making a formal complaint about the "hostile attitude" of corporation executives in the wake of her ageism case.

In a fiercely critical, 1,800-word letter to the BBC's head of complaints, O'Reilly said apologies and offers of work from Entwistle and his predecessor, Mark Thompson, were "clearly just a PR damage-limitation exercise".

O'Reilly, who successfully took the BBC to an employment tribunal after she was dropped from Countryfile three years ago, said she felt she had no option but to leave the BBC this year, just nine months into a three-year deal. She said it was "very quickly clear that I was not going to receive fair treatment" and alleged that a member of the production team on the only TV project she presented on her return, BBC1's Crimewatch Roadshow, "appeared to be on a mission to humiliate and undermine my confidence.

"One one occasion he was cueing me as 'Hayley' during a live broadcast and laughing," said O'Reilly. "When we came off air and I asked him why, he said it was because I reminded him of Hayley Cropper, a transsexual character in Coronation Street. I objected but the following day a picture of Hayley Cropper had been stuck to my sound pack for all to see. He derisively said he did not want me to eat with the team in the evening as I had to be 'fresh' to remember my lines in the morning."

The revelations will embarrass Entwistle, who began his £450,000-a-year role on Monday and used his first week in the job to declare he wanted to put more women on BBC television and radio. Entwistle said in various interviews that he wanted to see more women on BBC News, including a second regular female presenter on BBC Radio 4's Today, and more coverage of women's sport. Entwistle wrote to O'Reilly in January, when he was still in his previous job of director of BBC Vision, saying he "wanted to get in touch to thank you for all your help on the projects you've undertaken for us in the last year, specifically Crimewatch Roadshow, and to assure you we would like very much to discuss working with you again once your break was over".

The new director general said in an interview in the Radio Times that he did not know when she would be back on screen: "If she comes up with a brilliant idea, I would love to have her back."

O'Reilly said in her letter to Jessica Cecil, the BBC's chief complaints officer and head of the director general's office: "Apologies and offers of work after my tribunal win from Mark Thompson and George Entwistle were clearly just a PR damage limitation exercise as nothing has materialised. Despite the BBC saying publicly that it accepted the unanimous findings of the tribunal, what happened privately tells a very different story."

She said the lack of work on Radio 4, despite it being included in her contract, and her treatment on Crimewatch Roadshow led her to believe she was "never going to be treated justly or fairly so I decided for the sake of my health to step back". A subsequent TV programme idea that she pitched was not taken up.

O'Reilly expressed surprise that she had not been invited to take part in subsequent discussions of ageism, including her case, on Radio 4 and BBC1,She said she believed a senior executive had attempted to persuade programme makers not to include a photograph of her in a discussion about ageism in the media in BBC1's Sunday Morning Live, which was broadcast on 2 September. "One would think since my case was what Mark Thompson called the 'turning point' in the ageism debate, that I might have been invited to comment. Of course if this didn't suit editorially, then fine," she wrote.

"This cumulative action is not what one would expect of a fair and balanced BBC, but it clearly shows the level of animosity which exists and which has denied me my career."I won my case unanimously, but the attitude of some executives following my return to work shows a contempt for the law. The way I've been treated isn't worthy of the BBC, or what the BBC stands for."

A BBC spokesman said: "The BBC has apologised both privately and publicly to Miriam for what happened to her and, as an organisation, we have made sure we learned lessons from it. As recently as this week George Entwistle said he would welcome Miriam back to the BBC if she had a great idea for a programme – the same challenge he has laid down to programme-makers nationwide.

"It would not be right however for Miriam to appear on every single debate about ageism across the BBC as it would risk limiting the range of voices and opinions that audiences could hear."

The BBC and women

Today Sarah Montague is the only regular female presenter on Radio 4's Today. George Entwistle said this week that the next full-time appointment should be a woman

Panel shows Question Time chaired by David Dimbleby and Mock The Week hosted by Dara O'Briain were criticised in a report about TV diversity for featuring "token women"

Management The newly-formed BBC management board has nine men and three women, and this week Entwistle's unsuccessful rival for the top job, chief operating officer Caroline Thomson, said she would be leaving at the end of next week

BBC News Fiona Bruce, 48, told Readers' Digest that she dyes her hair to read the news, saying the presence of grey hairs wouldn't not be an issue for a man of her age

Come on Arlene - Strictly Come Dancing judge Arlene Phillips, then 66, was axed in favour of Alesha Dixon, 30. The show was criticised for using older contestants as "figures of fun".