Hi FX,
LVO is not so slow as you think. Infact, they treat numerous applications from Nigeria Citizens based in the UK.
In my own opinion, I think they are faster than AVO.
Back to your post..
Your timeline suggests you filed your application in September 2010. Is this correct?
Are you changing because you don't intend to go back to the UK or because LVO is just generally slow?
Have you done your Medicals yet? If you have, where was is done?
I would suggest you raise a CSE on this to LVO/AVO explaining you are no longer in London and state your current location.
Your application might be delayed a while because of this though.
this is the link for LVO - CSE https://secure.cic.gc.ca/enquiries-renseignements/case-cas-eng.aspx?mission=london
this is AVO CSE https://secure.cic.gc.ca/enquiries-renseignements/case-cas-eng.aspx?mission=accra
Hope this helps