Why do the armed response team come even after we've cancelled them?

The ADT control room seems terribly disorganised. On two recent occasions there has been a false alarm, and we have either called ADT immediately to report it as such (and stop armed response being sent), or have been called by the ADT agent and told her that is was a false alarm and armed responses should not be sent. YET, on both occasions the ADT armed responses guys turned up 5 minutes later. This is frustrating because of the time wastage involved and disruption in the middle of the night, but also because ADT has a policy that only a few armed response call outs are permissable a month, after which the client will be charged for each call. So, this potentially has a finacial impact for us too.