Sorry, I'm not rajkamalmohanram/rajanvnv, but there was a similar case to yours...they got a CAD bank draft from a bank in India, and OINP returned it to them. A couple of members who got drafts from the same bank compared their drafts...the one whose draft was already encashed confirmed it was the same. The member whose draft was returned appealed to OINP, who rechecked the draft and accepted back the package and the draft. Human error.
Is your bank draft drawn against a Canadian bank, it should say so on the draft? Scotiabank, etc. If you really think it's valid, then you should appeal/explain again. I hope for your sake this is an easily fixable case. At worst, they would have given you another 30 days to resubmit the payment.