My blackberry stopped working properly when I came to Pakistan and I cannot find a decent repair centre. The battery would take forever to charge, and then run down very quickly. Now it has stopped working completely. Are there any authentic blackberry repair centres in Pak? If not what is the next best option?

You probably just need a new battery. Try a new BB battery, not a cheap knock off and don't let it run below 20% on a regular basis.

Ditto the above. Definitely try a new battery first before anything else. And get a genuine BlackBerry battery from a reputable source, or do the best you can.