Thanks For your time jason, i really appreciate it.
For anybody wondering what the issue was as ususal something very simple.
i was using an absoloute path for the upload, which was causing the problem.
so if you have similar issues check that you are using document relative paths.
i was using a absolute path as the update page was a plug-in used by the framework builder.
I thought it would take the path from the page the framework builder was applied too.
this is not the case:
in fact it appears that the framework builder when including plugins, will process the plugin from the folder it resides in so using a path relative to the plug-in page is the correct way forward.