I've learned my English in the US and I know that I tend to use a simple past in places where English Grammars say I'm supposed to use a Present Perfect (e.g. Did you see the movie?). So, I'm trying to understand if the difference between but she didn't and but she hasn't in the sentence above is simply one between American usage and British usage, or if there is more to it.
From a purely grammatical perspective, if at the time of speaking she still hasn't called then but she hans't should be the right choice, at least in BrE. And yet, for some reason, I cannot bring myself to say it. Maybe I'm hearing it like if it was a tag question and I want to follow the tense in the main clause, I dunno.
Especially in its negative form, e.g. I didn't think she would call but she has, it does sound a little bit off to me.
Thank you for your help