It sounds like you may have posted your phone number on CL, I'm hoping I'm wrong there! Never post your personal information on CL - let them chat with you via email, if you get any warning signs stop communicating with them. I only give out my number once a time and date has been agreed to. And only if I feel comfortable in doing so.
Also, after we agree to a place and time, its set. If people try to change that, I tell them I'm unable to do that and insist on the original plans. Obviously, if we leave it tentative, that's not so much a problem. I've never had re-do plans work out - just lots of no shows. If the person is unable to meet the time and date they've committed to, I'm really not interested in doing business with them. In fact, I blacklist anyone who pulls a no show. I keep them in a special email folder labeled FLAKES and check it before working with anyone.
I learned that the hard way with ducklings. I had one jackass change our plans ten times, over the course of almost two months. I could have sold those ducks a dozen times in that period! What a huge waste of time and energy. And money! I had to feed those ducks for all that additional time. And it took a lot longer to sell them out of season, so I ended up with them for another few months while I desperately tried to sell them. Instead of selling fluffy little darlings, I was selling adolescents. Much different.