Google Calendar Search & Match to Database

I have a piece of software that another worker built in .net. However, he does not know how to make it do this one function. The software needs to log into my google calendar, where I have thousands of appointments. It needs to check the calendar to see if any of the records in the database (over 30,000 records) match any of the appointments in the calendar. The software should check both phone numbers and emails for a match. If a match is found, the software should change the status field of the record to "GC" One problem is that the export file of my calendar is too large to import into another account and I am not permitted to grant access to my calendar to a developer. So, you must be able to help me trouble shoot this issue as well as change the software. One idea that I had in order to avoid this issue is to have the software log into the google account, export the appointment data to an .ical file and then perform the matching function on the .ical file. This way, you would not need to log onto my calendar. At the end of the project, I would require the updated source code as well as an install package. I have provided the current source code as well as the .ical export that I recently made. This should be all that you need in order to complete the project.