Diana was unable to control the media regarding story lines over herself. The only way she influenced the media was by telling them where she was going to be if they wanted photos and having cosy chats with a couple of reporters, to ensure that she stayed in the news. The article from The City Journal shows this clearly, IMO. Even with the last pictures taken on the boat, the agreement was that she would pose and they would leave her alone for the rest of the holiday, as we all know that did not happen. Far from Diana controlling the media, it seems they said jump and Diana said how high.
Diana was said to be furious that Charles hosted a big birthday bash for Camilla, whilst she only got a bunch of flowers for her birthday.
I meant to ask where you read that Diana and Charles constantly telephoned one another, because it seems to fly in the face of all other accounts of that time period. Even Brown suggests that Diana went on holiday with Fayed to 'get at' Charles and the rest of the royals.