Dena Bank — illegal transactions done by bank

Address:

Mumbai City, Maharashtra

Bank erroneously transferred someones money into my account. Rs 50, 000/-
We did not report it as expecting a similar amount from other resource.
Bank transfers this amount from my other account in same branch without my info.
They said they have right to do so. I told them that money not ours so definitely we don't want, but you have to atleast inform us before transferring.
They also charged interest of rs 23, 000/- claiming it as loan interest on rs 50, 000/-
Till date bank refuses any wrongdoing on their part
Must have writen atleast 10 to 15 letters but no response