Thanks you Rumel Bhai for sharing this info.
But Sorry to hear about the news for him...
I think there could be the reason of rejection due only 15days time of any FDR and there is no any other valid documents of the source of fund for creation only FDR account.
It could be good for him if he can maintain the account and transfer the fund in different time and different way then it would more reliable rather only very short time FDR made confusion of POF for case officer.
Also if he maintain similar amount in other account so when case office raise the issue that time could cover for last six months for his latest bank statement with certificate could be a back up POF. In that case his agent should guide him in the correct and right way....