Outsurance refuse to acknowledge written cancellation

I have submitted a written notice of cancellation, and asked for a written confirmation. Since then, Outsurance have been trying to phone me at all hours of the day. Obviously they want to try and sweet talk me into staying with them. But this kind of behaviour is exactly why I am leaving. A sinple request such as "please email me, because I am unable to take calls" is completely ignored.

OUTSURANCE: THE ONLY THING I WANT FROM YOU IN RESPONSE TO THIS MESSAGE, IS A WRITTEN CONFIRMATION OF MY CANCELLATION!! I DO NOT WANT A SINGLE PHONE CALL, JUST AN EMAIL TO CONFIRM MY POLICY WILL BE CANCELLED