Since the beginning of the Corona Virus pandemic and the adaptation to distance learning, I have had to adapt my classes to hold exams via video calls. In previous semesters when I've had students with special accommodations (i.e. entitlement to extra time on exams), the students would generally go to a different office where they would take the exam with a special proctor who was aware of their entitlements. My institution however has levied this burden to instructors to keep track of students' various time limits on exams.
A student of mine with an extra time entitlement had emailed me to confirm that I was going to honor this. I didn't have the time to respond to them via email prior to the exam, but I had sent this student a private message via the video call platform to confirm with them their extra time and wrote out instructions for submitting their exam. This student however never read my message, and as a result submitted their exam prematurely claiming that I hadn't confirmed their extra time entitlement. Because the video call platform doesn't record private messaging into their transcript, I have no physical evidence to show the student that I had messaged them at the start of the exam.
I'd like to know what would ethically be the right way to handle this situation. I want to honor this student's time entitlement, and potentially give them the lost time to complete the exam, but I'm already at a place where I have to go over the exam with my other students. I'm not sure what the correct way to handle this situation is. It's frustrating because there was a second student who had a similar entitlement during the same exam, and they read my message and took advantage of their extra time.