Advice in dealing with BGP prefix hijacking


I'm looking for advice on how to deal with a US ISP (names withheld to
protect the guilty) which seems to repeatedly fat-finger our IP space
into their BGP announcements, and then gives us the run-around when we
call them on the phone, since we're not their clients...

Happened twice already, took several hours to fix each time, and I'm
looking for any ideas, opinions, and war stories that would help me
figure out how to discourage them from repeating this type of thing
in the future...

Thaks much,