Package marked undelivered that was delivered

I was dinged for one "undelivered package" that was in fact delivered. The location was so remote there was no cell service, but I entered the info that the package was handed to the customer and went about my route. Did not realize until later in the route that the package was still marked "open." I called Flex Support and explained the situation and sent an email but my rating was still downgraded for one "undelivered" package. Is there anything I can do - or if this happens again, how can I get the app to reflect that the package was in fact delivered? Thanks for any insights you can share.