"updating it will take 2 days"
The updater makes a calculation, based on the download rate applying at the time. The update period normally changes rapidly, once the download gets under way - no update will take 2 days to download and install. Often, if a machine hasn't been used or updated for some time there will be a large amount of data to download, and this can extend the update time.
Keep trying, and make sure that nothing else is running on the computer while the update gets under way.