Whilst there's no doubt this Kia guy will always look after his own interests, and he clearly has an axe to grind with City, and vice versa, it is too simplistic to put the blame for this 100% at his door and nowhere else.
Tevez is not so simple that he will not express his own wishes. It is his reputation and future being gambled here. He clearly has and has had gripes with the club.
I'm not saying he's in the right, I don't know the facts well enough. It certainly appears City has been very flexible with him. But there is surely more to this that just "Greedy Agent Seeks Move for Zomble Client".