If you're at the arguing with the textbook stage you must be deep into the madness (what book do you use?) so maybe you know the worst of it. I know people who have never recovered from some prepositional pronouns though: for some reason uaim has that effect.

My fall back when a textbook insists that something I do is horribly grammatically incorrect is that it's a Donegal thing. You've got good odds that what you're doing is correct in one of the dialects...