Forum:IP unblocks itself

We have a problem on the Morphin Grid wiki. We've blocked IP address 184.15.4.24 several times, for inserting false information. But the ban never lasts more than a day before being mysteriously removed (the block log doesn't mention it ever being unblocked, but the deleted contribs proves that it is). What's going on and how do we make sure that the block sticks? Digifiend (talk) 14:02, October 15, 2012 (UTC)
 * The IP address 184.15.5.182, believed to be the same user, has also been unblocking itself. It has been blocked before and yet again returns anyway. It has never been unblocked, but the deleted contribs proves that it is still able to edit. How is this person able to get past our blocking their account to spam our wiki? Nbajammer (talk) 20:13, October 15, 2012 (UTC)
 * This shouldn't happen, please send a message into w:c:Powerrangers:Special:Contact/bug to get staff's attention --  Random Time  20:17, October 15, 2012 (UTC)