Missing karts from December
I was one of the unfortunate people who lost 10 or 11 karts with the update to version 1.6. I received an email from Nadir a few days ago asking me exactly when the karts went missing. I replied and the next day I went to play ABGo and my karts were back. BUT Rovio put me back to sometime in October so I lost all progress from the last 4 months and all multiplayer was lost. I ended up losing about 3,000 gems (1200 were given to me in January because of the missing kart issue) and 250,000 coins and a kart that I won in a weekly tournament and all of my golden eggs from multiplayer. They are refusing to give me any compensation implying that I am a cheater.
So the moral of this is, don't ask for your karts back!