I see the discrepency. You have Size 28 in the auction title, but down in the text it's Size 30 (2nd line below description header).
You really don't need to make that correction from Auctiva. Simple text changes to description are best done using the ebay Revise listing feature.
To make that change use the ebay Revise Listing from the listing page (on ebay) and locate that "30" in the description section. Just edit that 30 to a 28 and follow steps to complete and submit the revisions. Note, I always Preview my changes before I complete, just to double-check.
That should do the trick!
Danno