The original first post is over a year oldI thought we're at 10.5.6so how can have all updates?
Anyway, I had the same issue a couple months ago, and it ended up being a broken charger. So I either suggest you find someone with a Mac close by and try his/her charger, or go to that service store you talked about and ask to use one of theirs.
If that won't work, you will have to send it in I'm afraid.