Man! That's a shame. Looks like it doesn't work anymore. If anyone has found a workaround, please, do mention!
It never worked to start with, it is based off your messenger, so if you have someone who you have only just added as a friend at the very top of your messenger, they will be the first number you find But it is still there, just search for friends and look for 'mobilefriends'
Thanks Villan4eva for that info though this post is old it was useful information . I think almost all facebook hacks are scam pop ups to buy this or put a virus on your device. Correct me someone if i am wrong it would be interesting to play with.