Monies borrowed from the Sinking Fund must be repaid via a Special Levy, the structure of which must be resolved by simple majority at a General Meeting of Owners within 3 months of the date of the initial borrowing. So the Owners Corporation has no choice other than to pass the Special Levy!
Before the Agenda for the prescribed General Meeting is prepared, you would do well to ensure that the compulsory Motion about whether or not any spending restrictions are placed on the Executive Committee (E/C) is included, and that the Meeting invokes that by requiring appropriate restrictions on spending for any / all matters relative to the approved budget for each (e.g. <5% above), so that the E/C’s profligate spending habits are curbed.