Hi 
Ahh, i had that with a different package, also from a PPA. Try editing the
sources.list to remove the PPA.
There is a way to do this from the command-line but i think you would need
to install the purge-ppa (or something) package first, which you can't do.
So, best way is to open Synaptic and click on
Settings - Repos
and untick the PPA.
If you really must stay on the command-line then maybe
sudo cp /etc/apt/sources.list /etc/apt/sources.list-2014-08-20
sudo vi /etc/apt/sources.list
(in vi you need to press i to make it let you edit. When done press Esc
and then
:w
:q
the colons show vi that you are issuing commands). The cp command is just
to make a back-up and i tend to stick the date in reverse order at the end
to help me sort out my back-ups.
Whichever way you edit the sources.list you will need to update the list of
repos by doing something like
sudo apt-get update
THEN it should be possible to use that -f tag
Good luck and regards from
Tom 