Even if you are on a BES with OTA sync you can still use the Desktop client to force a wired sync.
If your BES Admin has a policy prohibiting Desktop Sync you can try turning Wireless Calendar Sync off for a bit and then turning it back on (see KB05340
). That can force it to rebuild the database. It may not fix the particular problem you may be having though - Calendar issues can be stubborn. For some problems we have had to delete the Calendar DB and then force a sync but again, that's over the wire using the Desktop Manager.
In a future version there is supposed to be a synchronization function for calendar on the handheld, similar to the "Reconcile Now" function on the Inbox. Hopefully that will be a quicker way to resolve some of these calendar issues.