What is the best facebook Chat app on the windows mobile app store?

I recently deleted FIM due to its constant crashing and when i went to re-download it ... It wasn't on the store :-( So now I'm trying to find a decent Facebook Messenger App.... Any help ??? Considering the official facebook app for windows is appalling (Just a heads up my phone is the Nokia Lumia 800)
And there currently isn't an official Facebook Messenger app available on Windows (UK)
And my Integrated system isn't as fluent as it should be, Receiving messages on it is someone temperamental ....