It happens a lot zombie. My advice...get use to it. Seriously not much can be done. Clerics will be abused and forever abused. I even made a thread for it. Clerics require a lot of patience because most players will not use stones or will only "use the cleric". e.g. Fighter parties a cleric but takes all the drops and demands healing.

MT is bad but I am sure with the new Apprentice/Master system it will only get worse. At higher levels kill stealing is not so bad more so because not many people get that high of a level. A lot of people make characters get them to 20+ or 30+ and then say oh I quit because it is too hard. So just try to grind and ignore people. Or just....

...them.