Struggling to increase my earnings due to constant Timewasters

I am in the UK and charge higher than average rates (but based in and and only touring in big cities ) so this isn’t a problem and I do get clients . However I’ve been stuck earning the same decent (but not amazing ) amount of money because I only seem to get 30 minute , 1 hour and sometimes 2 hour bookings . You can only do so many of those so my earnings haven’t changed in 2 years . The girls who make the most money seem to do it by having long bookings but even though I get many enquiries for overnights , full day , FMTY or even 3-6 hour bookings they never happen and they just stop replying or ignore me when I ask for deposits . What am I doing wrong to attract so many Timewasters?? What’s worse is so many of these requests seem so legit and they are asking all of the right questions not just u avail bb . But they always end up disappearing .. I’m at such a loss of what to do .