lost songs in iTunes-iphone sync

Hello,

I purchased an album a few weeks ago using the iTunes store on my phone. I have recently updated software on my phone and transferred purchases before doing so, but, for some reason, iTunes has only synced hall of the album - 2 copies of all even tracks and no odd tracks. When I go to the iTunes store it tells me I've purchased the album, but I can't figure out how to download already purchased songs. I have tried to re-transfer the album from my phone, but receive message that it has already synced.

Any help appreciated, I am rather frustrated as remember this being easier - iTunes just seems to be becoming more and more infuriating!

Thanks very much.