Just tell them: "No sorry, we can't do that. So, should we sign you up for our annual plan (2 months free!), or would you prefer paying month to month?". If th

Just tell them: "No sorry, we can't do that. So, should we sign you up for our annual plan (2 months free!), or would you prefer paying month to month?". If they need your service, they won't leave. If they don't, they will, but that teaches you something about your market. Either way, you win. Btw: two months is substantial, it's a 17.5% discount.