you need to suggest to the repeater owners that they put an accept list in
their settings.  My repeater is set up such that you have to apply to the
echo link operator to get approved.  We aren't attempting to be "exclusive"
but rather avoid just what you are describing.  In previous installations I
have heard non-English speakers tie up a machine locally via echo link, such
that the control operator couldn't break in to shut echo link down.  A good
resource if used appropriately but if left wide open it can be a pain.

Brian, k5in