I haven't noticed that kind of problem, but there's a spot for notifying Amazon of discrepancies like that. Look for a link that says "Report incorrect product information" directly under the description. I believe you can expect the mat to be the dimensions stated in words rather than pictures, but they need to fix the confusion. Amazon has an excellent return policy if the problem is their fault.
I bought a Grace Tru-Cut mat from Overstock.com at a good price several years ago and have been very happy with it. I don't know if the same one is still available.