Tom,
Honestly since this happened over a month ago, I cannot really remember what happened (then or before).
I can tell you these facts:
– I think when I installed the Plugin (cannot remember when, but it was a while ago) I set the schedule to “once a week”
– I have a manual complete (offline) FTP backup from May 12, 2012 stored on my computer. This folder backup contains four WP-Backup ZIP-files in the subfolder wp-content/backups (2011-12-14, 2011-12-21, 2011-12-26, 2012-05-11)
– atm the plugin is set to store “once daily” and keep 10 backups
– online on my server, wp-content/backups contains 12 backup ZIP-files (2012-11-13 through 2012-11-22)
– the plugin admin page (Tools, Backups) shows a list of 10 backups (2013-01-12 through 2013-01-21); I cannot find those files on the server (obviously they are not in wp-content/backups, see previous bullet point)
Before I change/delete anything, would you like me to check out anything else?