Pimp Problems

I work as a contractor with IBM as the client. I don't work as an employee of IBM. I technically work for an contracting agency that IBM hired to find me. I call them my pimp. After all, they get paid to have me work there. Last week they called me into their office to sign some papers that were outstanding. One of the forms was permission for them to debit my checking account should they over pay me. I refused to sign it. We have been fighting it ever since. They claim that I am required to sign it. I don't care. They claim that all their employees have signed it. I still don't care. I am going to ask them for a form that allows me to debit their account should the accidentally under pay me. On Friday the manger called me to "get firm with me". He failed to convince me and I told him that it is going to take one hell of a lot of persuasion to get me to change my mind. I think that they feel they have a trouble maker in their employ. We will see what happens. Perhaps I need to fire them and find a new pimp.