This can be (a) annoying and (b) soul destroying. It can happen for one of two reasons, genuine spate of TWs, or someone trying to demotivate you. Like you people need to plan to visit me(well apart from the late night daft texters/folk in town who've had a few and think it'd be a good idea to get the local prossie to visit their little room above the pub
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Two ways of dealing with it;
1. Ask for confirmation or callback at a set time, either 1 hour before same day or first thing in the morning.
2. If you get a reliable regular booking for the same time accept it, agree confirmation times for all and tell the newbie on the day you can't make it can they make a different time?
Whilst it's galling if the newbie is genuine, most genuine guys will accept this and you keep your sanity. I find most of the time I don't have to do this because I have plenty of regulars booking in advance, and 50% of newbie's cancel anyway. I'm also pretty chilled these days/not interested in taking a lot of bookings and although I hope a client new to me does make it, I don't rely on it.
I also recently stopped offering weekend bookings most weekends, because I was fed up of being 'available' and then being mucked about, putting things aside for folk who were just rude or 'forgot' their booking, or went out drinking and were too hungover/bookings seemed good idea drunk but not when sobered up. Family and close friends work 9-5 weekdays and I preferred to have time set aside for them in advance, rather than be up in the air chopping and changing all the time.