When phoning to ask for a piece of information, unless you are sure the customer has screwed up, don't use language like "you didn't give us your..." as if you are in the wrong, you give the impression you are blaming the customer. Instead, assume you screwed up somehow or there was some miscommunication. Language like "we don't seem to have your..." is nicer.
Yes, my recruitment agency lost my Tax File Number Declaration. They phoned me with "you didn't give us your Tax File Number Declaration" when in fact I did. In their office. And handed it to them. Signed. With my Tax File Number on it.
Kind of interesting that they've discovered this today, when I was told my pay would be in my account by Wednesday.