how to un-warp my cutting mat?

I hope this is the right place to post....does anyone have a way to completely flatten out a cutting mat?  I have tried soaking it in hot water, ironing it (with a dishtowel on top) and then stacking big heavy things on top...nothing has worked so far.  It really drives me nuts.   I can work with it, so a new one is not a "need" but a "want."  (Darn it!)  Just wondering if there were any novel ideas out there.  Thanks!

Rachel

I've heard of other people having this same problem.  Some can get their mat to flatten, but others have no luck.  The problem occurs when the mat is warmed up for an extended period of time then allowed to cool.  The only way to fix it is to warm up the mat again and then allow it be cool while pressed flat.  It sounds like you've tried this so I can only suggest that you try again by warming it up and keeping it warm for an extended period of time (like leave it outside on a hot day), then bring it in and press it under books or a mattress for several weeks.
Some mats are irreparable.  You can cut off the warped parts and try to salvage what you can.  You just may need to buy a new mat. 

lay it flat in the sun and see if that helps.  If not, wait for a 40% Joanne's coupon and get another and use the warped one for gluey gooey crafts!