How can I strengthen my submitted graduate application?
For the sake of efficiency and fairness, candidate selection is a purely administrative process, based on submitted paperwork only, and handled by academic staff that adhere to strict rules and work ethics. You should not disturb them, nor should you hope for any good effect of doing so.
If you want to enhance your chances, then apply in parallel to other universities or/and other master courses. Submit paperwork that excels in contents and layout.