I physically delete all images from the files media/k2/categories (and items) also delete them from K2 back end then upload new images via K2 component but the original ones still show on front end even after 3 days and none of the images showing on the front end are actually in my files?

Joomla cache is off, permissions writeable, Gzip Compression off, cleared browser cache in all main browser types also restarted browsers and even turned computer on and off but nothing will rid me of the old images?

This is sending me crazy here. Please can someone advise?

Using Joomla 2.5.6 and K2 v2.5.7