Repository Mirrors - how often are they updated

[Gavin]

Thanks for those replies - I can now assume that the iinet repos are updated
frequently.

Assuming now that the problem is at my end, and since apt/synaptic work fine
(hence my sources.list is ok and connection to mirror is ok), then maybe the
problem is with the update notifier/manager.

Removed and reinstalled:
 update-manager, update-manager-core and update-notifier.

No difference. With sources set to iinet, (either http or ftp protocols),  the
system is reported as up-to-date, with any other sources there are currently 17
updates of over 62MB!

Am using Feisty - don't know whether that's relevant.

Just trying to exhaust all possibilities before contacting iinet, or giving up
and changing the repo sources permanantly 
(would prefer to keep iinet ones though!).