I would just send her an email instead. Explain that the appointment time given won't work for you, and ask if there is a way you can try to get your CIC file status.... sometimes they require a consent form... sometimes not. So, you *could* try to just offer the specifics for you and your sponsor (case number, DOB, address, PPN, etc), or you could wait to see what she comes back with.
Generally speaking, if you tell her that you were unable to get the time away from your employment duties, they should be pretty accommodating.