Raul,
I agree with your reply 100%.

And in response to Mateo..

I speak from a lifetime of working in the high end restaurant industry and dealing with the public. Yes, you can certainly put your energy into trying to educate everyone who takes advantage, or you can simply put a note on the tables stating what your policy is and save yourself the stress of trying to "educate" every potential offender. It's really a simple solution. The fact that you want to continue to confront people is perplexing.
As to you taking my words out of context and making assumptions?
My response is..

Cheers
I really do wish you the best.