I'm looking at claiming against the halifax, how successful are these claims normally?? any guidence anyone can give me to start on this. Please help

hey guys, looking into claiming my charges back from the halifax... got a letter yesterday regarding an account that i haden't used, went to the bank today to get my wages out and they had transferred money from one of my accounts to the other.. i phoned them from the branch and they told me that they were well within their rights to do this and would not refund any of the money that they had taken yesterday into my account. whats more one person told me one thing and another told me something completely different. the charges i'm looking at claiming back total just over £3,000 approximately. what would you recommend for me to do??