Under what circumstances can a banker disclose the secracy of a customer account?

What is relationship Banking?

A issue an 'open bearer' cheque to B for Tk. 5,000 who strikes out the word 'bearer' and puts crossing across the cheque. The cheque is thereafter negotiated to C, D, and E. When it is finally presented to E's banker, it is returned with remarks, "Payment countermanded by the drawers". In response to legal notice from E, A pledge, that-

(i) The cheque was issued to B under threat from him ; and
(ii) The cheque was altered after it had been issued and thereafter he (A) is not bound to pay the cheque. Please discuss whether A's argument is valid or not. Give reasons.