I really dislike services which make you call to cancel. There are some in the US, too. The OP could use the Times model to try and convert folks to a longer-t

I really dislike services which make you call to cancel. There are some in the US, too. The OP could use the Times model to try and convert folks to a longer-term, discounted plan if they are enjoying their trial. But too much upsell and your conversions will drop.