RuneMate and the game client need to both run on x32 bit Java. Remove any x64 bit Java installations and RuneMate, and then install RuneMate again – it will automatically download the correct x32 bit Java version.
Go to the correct bot author forum for the script your running and ask nicely for a refund.
It the runescape client crashing. Not really something runemate staff can fix. Contact jagex and wait a year and you still probably want have heard from them..