Well, I certainly can't fault AT&T not giving her Brittney's info. That wouldn't be right since she is not Brittney's mom or dad....and I can only speak to my own situation.
As I have related here in years past, when my own son disappeared, LE said that I could try to contact AT&T and see if they would give me his cell records, since his phone was paid for by me and his dad. They said if I could get them, then they would not have to go to the court to request them. Investigators felt that AT&T would balk at sharing that info with me and they were right. But I pressured hard...I cried (and not as a put-on, I was sincerely desperate)...and begged...and they caved. They emailed all the records that day, so I had them almost immediately. But the rep stayed on the phone with me for a while giving me his most recent calls, leading up to his disappearance and then the one call he made right after.
This "waiting for the records" to get there makes no sense to me. We are in the digital age. GET THE RECORDS, dang it.