On the one hand, I've worked on a helpdesk and know exactly how annoying some users can be.
On the other, is it right to just switch off your 1000 most annoyed/annoying customers?
Sprint seems to think so.
This is probably a good business decision in the short term.
[link|http://www.theregister.co.uk/2007/07/11/sprint_boots_annoying_phone_customers/|http://www.theregist..._phone_customers/]
Based on the content of that story, I think it was the right thing to do; if you're calling 100 times a month, you're more aggravation than you're worth.