1. First check all the documents you have uploaded with your application. It's very unlikely that they'll mark your application incomplete unless they have found any of the "mandatory documents" missing.
OINP is very generous and raises ADR in case any of the supporting documents are missing to process the file further, however in your case it seems that mandatory document(s) was not sent and hence they choose to withdraw the application and refund your fees.
I suggest you write an email to their office along with an explanation letter support your case with all documents you have already submitted to them (don't add any fresh documents). It may be possible that the concern officer must have missed reviewing one of the documents and choose not to process your application.
I hope you get through this difficult phase soon.
Good luck !
