MOH1979 it has to be Accra as that is where PR is processed.
Gamer, if you have documents to send, use DHL to send your passport. DHL Express from Nigeria takes 2 business days to get to the VO in Accra. If you are just sending your passport and there are no documents to send, you can use VSF. Just note that DHL is quite expensive. It costs N13k just to sent to Accra and for them to pick up, it is another N18k or so. For VSF, sending and picking up is almost N8k buy I do not know how long it takes them to deliver it to Accra but I think they must send stuff everyday.
Hope that helps.