Let the users with the ability to cancel online as you let them subscribe online
It would be better if you give the user the possibility to close its account (it cancels order) with you as it is for online registration. If you want to work with users from all countries, avoid the trouble that their have to contact you by phone and expenses that you can not imagine the phone call from some countries to yours. Finally you offer a solution online but you minimize the advantage of forcing the user through a single way to join you by phone that is not the best online solution.
We run a monthly subscription site using 1SC as our front end and recurring billing system. It is killing us that users cannot cancel their own subscription with us. As we grow, this is taking more and more resources to process the manual tickets and phone calls that come in. Suggestion is to allow an autoresponder process to connect to the cancellation request, so that a downsell offer could be made.