I can't speak for Certification Bodies other than the one I mostly work with, but currently they do not permit an NCR to be closed during an audit.
Up until a few years ago, they did. I suspect that it was due to the fact that an NCR that was rushed to close before the end of the audit usually had poor root cause analysis and a resulting poor corrective action. I also suspect that no longer accepting NCR responses during the audit was driven by the Accreditation bodies, but I don't know that.
On a slightly different tone, there is nothing wrong with discussing an NCR, even down to the last few minutes of the audit. There is nothing wrong with providing additional (already in existence, not newly fabricated) information to strengthen your position. I saw this recently, when the auditor was ready to write an NCR over lack of validation of a special process. The client was able to successfully defend his position that the process in question was not a special process, that is, that the outcome could be fully verified and validation was not necessary.
It sounds like you need to take the hit and then work on an effective root cause analysis with an accompanying effective corrective action.