I can sympathize. I've been doing some tech support stuff at work and it's had me in tears a LOT.

You're feeling a lot of pressure from your trainers and from yourself. It sounds like you can find a lot of weaknesses in your work--but you can't change everything at once. I'd suggest, MOnday, choosing one thing to focus on during all your calls--one thing that would help satisfy your supervisors, like taking the time you need to find the right information, or getting the information about one specific area correct. You can't fight a war. On all fronts, you've got to choose your battle.

And don't forget to give yourself credit--for your willingness to be honest with yourself, for your desire to do well, for your willingness to learn.