When these bottom feeders call, I actually make if a fun part of the day, and get out some frustrations that come with being a business owner as well. When they call (guy), and then ask for the owner, then ask how your day is, I just reply.. "it was good until the syphillis eating co** su**er called me, and by the way how is my favorite he-she?"... there is usally a pause and then they hang up. I have a bunch of different lines, but this is just one example. I hate being rude to anyone and it goes against the grain, but when you figure in how much it costs you and the delays from stopping everything to talk to them, it all come out even and I guarantee you will feel better!