What action can I take against the bank since I have had no access to the money from the business for bills that I am responsible for?

I am 51% owner of a corporation. My business partner and I split up and he withdrew all the money from business account. I found out that a different bank allowed him to open another business account without me being present. He told the bank he was the sole owner even though all documents clearly have my name on them. When I found out about this account, I went to the bank and asked to be added onto the account. They refused based on what my ex-partner told them. They said in order to be added they would need a court order. I think that's a cover up because they know they did something wrong.