The Duke and Duchess of Sussex have piled fresh criticism on the British royal family in new episodes of their Netflix documentary series, accusing their aides of being part of media attacks.

In the first tranche of episodes released last week, Prince Harry and Meghan launched fierce attacks on the media over their treatment, some of which they said had been racist, but the royals themselves escaped relatively unscathed.

However, there was greater criticism of his relatives and their aides in the final three episodes released on Thursday, accusing them of not just failing to prevent negative coverage in the media but actively encouraging it.

“It was already clear to the media that the palace wasn’t going to protect her. Once that happens, the floodgates open,” Harry said.

The couple were also shown talking about a former senior aide to his elder brother Prince William, the heir to the throne, who provided evidence in a legal action Meghan had brought against the Mail on Sunday newspaper that had published a letter she had written to her estranged father.

“It’s your brother. Not gonna say anything about your brother, but it’s so obvious,” Meghan said.

In his evidence the former aide, Jason Knauf, suggested Meghan had been aware at the time that the letter could leak.

“That’s why I’m now living in a different country because all the comms (communications) teams basically like try to outdo each other,” Harry said.

“But this is the contract, the symbiotic relationship between the two institutions working the best that they can.”

Netflix included a statement from a representative for Knauf, which said the claims were “entirely false”.

The episodes were released just hours before King Charles, his wife Camilla, William and his wife Kate along with other royals will attend a carol service at London’s Westminster Abbey to “recognise the selfless efforts of individuals, families and communities across the UK”.

While the couple have won awards and plaudits from some across the Atlantic for their charitable and human rights work, back in Britain a hostile media accuses them of seeking to make millions from their royal status while constantly attacking the monarchy.

Newspapers have also cited former unnamed royal aides challenging the accuracy of the couple’s narrative in the documentaries.

Both Buckingham Palace and William’s office, Kensington Palace, have said they will not comment on the documentaries.

A royal source also said neither the palace nor representatives of William or other royals had been approached for comment for the series itself, contradicting a Netflix statement that said they had declined to comment.

According to initial figures cited by the BBC, some 2.4 million viewers in Britain watched the first episode on the day it was released, although the senior royals themselves have steered clear, royal sources have told newspapers.