This is an update to my situation with her. I think anyone working with her might find this interesting, as I've found a way to make sure she pays.
Alex attended her session of the 17th of September. I asked her up-front whether she was ready for her session (I wrote this to sound like a "yay, we're about to do your commission!" but my aim was to get her to state that she had the following two hours to spare) to which she said yes. I then said that in order to provide her with her consultation time she would need to pay for the first, and this session.
She said 'oki' but 10 minutes later no payment had been made. So I got on with other things but frequently checked for payment of her invoice, and every 10 minutes sent her a message nudging her to do so. I've attached screenshot to show you guys the way I spoke to her during this time. Note: I played hardball knowing what I knew from this Artist Beware thread; I'm never this harsh to clients normally. I have debt recovery training and experience so drew on that.
To further clarify the situation, the echeques that I received from her took 5 working days to clear, but they did both clear, I was able to transfer the money to my bank account, and I am content with this situation. Despite my having a strict talk with her about paying and making sure I got the money before booking anything else, she booked another session within days, on Saturday evening for Sunday evening.
I sent her a message to remind her of a) our agreement about payments, and b) that her last two payments had taken 5 working days to clear, so I would only be able to accept her booking if she could get the money to me faster. She said to cancel the booking, but by then we were within 24 hours of the booking so I held her to my cancellation fee - and told her to cancel the appointment herself. I wasn't about to run around cleaning up an admin mess she'd made. She did indeed cancel the booking.
In short, I would recommend that if you need money badly enough to decide she's worth your while, then insist on invoicing her, and receiving, and banking, your money before you do any work. Then she seems to be fine.
After the events in the transcript provided, I sent her a new £50 invoice for another 2 hours of consultation time which she paid, then took a few days to book in with me. She also blocked my account. This is fine, since the actual consultation will be carried out on another account by my partner, who also does consultations, and I appear to still be able to email Alex. Going forward, I aim to either have my partner ask, or ask myself, whether she wants another session in the future, and send her an invoice in anticipation of her booking her next one.
Just keep your boundaries very firm with this person and make absolutely sure you get your money up-front, and you should be fine.
Our conversation here.