CIC instruction guide says:
Updating your contact information
During the application process, you must advise us of any change of address or telephone number. You can do this by going to Change of address or by consulting the How to contact CIC section at the end of this guide.
Note: If your personal situation changes (for example change of marital status, birth of a child, or you wish to withdraw your sponsorship, etc.) after you have submitted your application, you must contact us.