Britain's Jenson Button has justified his decision to leave BAR for Williams as the dispute over his future moves towards a conclusion.
The issue will be decided by the sport's contract recognition board with both teams claiming to have binding contracts with him.
"I don't like the way it has been handled at all," said Button.
"I think Williams are the team that can give me the chance to challenge for the world championship."
Button added: "I'd rather it had been a lot easier - It's not a nice position to be in.
"We had an agreement to be with BAR for two years, I honoured that agreement and I think I did a good job.
"One of the reasons why I want to move on is because I am not 100% happy at the team, and one of the reasons I've not been happy is that there are issues
with the contract."
The 24-year-old was confident the contract recognition board will approve his switch to Williams.
"I think they will understand our position and we will be there next year," said Button.
"I wouldn't be going through all of this if I didn't think it was possible.
"It's never 100% certain but I'm pretty sure I'm going to be with Williams next year.
Button, who began his Formula One career with Williams in 2000, said the move was a signal of his ambition.
"I need to move on and be with a team that can challenge for the championship over the next two years," he said.
"One of the reasons for the move is the resources Williams have, compared to most F1 teams, is staggering.
"They obviously didn't have the best car this year but they know that they know their mistake and they've worked on them and made improve, which they will do in the future."