If a member just stops coming, the consultant has to contact them to find out why. If you don't want that to happen, it is probably simpler for you just to send a note saying that you won't be coming back - no need to say why or give any personal information.
That way, you don't have to speak to the consultant that you don't like, and she doesn't have to waste time/money chasing you up. It's a win/win situation.