Stephane issued a cheque in favour of Rosaly. However, when Rosaly presented it for payment it was dishonoured and returned marked "R.D." It now transpires that when the bank clerk was checking on Stephane's balance she checked on the wrong account and as a result the cheque was dishonoured under a mistaken belief of lack of funds. Explain Stephane's rights against the bank and elucidate on ratification as used in the law of agency.