@kesty - True. I still don't really understand - are they not charging anything? It doesn't make sense.
@Cyrax - The first fight I couldn't get past was when you help out the actors guild group, they take a portal into a prison dimension. You follow them in to save them, and get ambushed from both sides. None of my guys could survive long enough to do any damage, and I got so many "weapon ineffective" messages, it was a hopeless fight.
After bailing on that, I tried to head to the Harper's building, where Jaheira was called to. Again, it's an ambush, but you can't even prebuff some spells outside (magic isn't allowed outside,) and generally just got overwhelmed in there too.
This time, I'm not exactly sure what the difference was, but it worked out much easier. My main character is a much stronger fighter class (also imported from BG:TotSC, so probably has better stats,

) and have mostly abandoned summon creatures for other spells.
The AI mages are so dangerous. They have those annoying Horror/Fear spells, but also completely overpowered spells. Disintergrate? That's an auto-kill spell that can't really be protected against. Have it cast against your main char, and it's over.
Then as soon as they see you, they cast five or six protective/anti-damage spells, so all your attacks become ineffective, and Dispell Magic doesn't even work. I think there's a Remove Magic spell that removes protections Dispell Magic can't, but I've only just made that a memorised spell.
Yeah, it's tough, but I can make some good progress now, and am no longer being overwhelmed by the mass onslaught of side-quests. I'm beginning to like more of the side-quests too.