How do I keep my static IPs?

Hi,

I lost my Static IP block today, after having them for about a month.  The tech told me that there was a conflict so they reassigned me new ones, but did not tell me.  And I noticed several posts on this topic, but no one says how I can keep from having them taken randomly.  The tech said he had the person on the phone check to make sure the new IPs were free, but a similar thing happened when I first got the Modem and those were suppose to be free.  I know they will refund the static IP fee that I paid, but I would prefer not to loose them, because it takes me all day to get my domains reset to the new IPs and I had to wait 3 hours for the tech to stop by and check the modem.  Anyway, is there a way to keep this from happening again?