Dear (billable by the hour) consultant-
You are brought in to help us find a solution. You are not to bring the one solution that you know and try to fit us in there. You are to find a solution that fits the client, not a client that fits the solution. So next time please present at least two different solutions (see here why), otherwise we are going to bill you for our time instead.
[ Inspired by discussions with colleagues from both the private and public sector ]