[Cable] Transferring in from Fido

I just called EBOX and set up new cable service. It would be a future dated transfer from my current provider Fido. Now that this part is done, do I still need to call Fido and advice them of my cancellation, or would the transfer automatically result in a cancellation with Fido? Speaking of that, Fido would actually still owe me partial monthly fee, not sure how they would refund that (if at all).