auto responder to twitter posts

I need an auto-responder to twitter posts, i.e. if a user tweets 'I need a plumber', then we want to send them a response that they can post this as a job on our website (Australia only). I think there are some packaged software tools that can do something like that!? Either way, we would need someone to set this up for us. At the same time, we do not want to spam people so it is critical that our auto-responder is relevant and that will require some fine-tuning of trigger keywords. Keywords: all construction trades