Is it theft to withhold my money this way?

[Jennyt3]

Hi all! Quick question and long story short:

Did some work back in April for a woman I have worked a lot for the last few years. Basically I am a freelancer and she passes on work to me, and takes a cut as a finders fee or whatever. Work completed. She tells me the client has sent her the money. Then nothing for 5 weeks. I send messages, she ignores them. I keep trying, she gets abusive. Anyway, turns out she spent the money she was sent to forward to me on paying a fine that her and her husband got. And now she has no money to pay me. So it's like she has used my money as a short term loan without asking my permission!
Is this theft? Or is it a civil matter? She doesn't seem to see the issue with it, but as far as I'm concerned, she never had any right to that money. It's over £1000 by the way.

Thank you in advance if anyone can help.

[Amethyst]

Any contract / written agreement between you and this woman? Do you invoice her for the work each time?

[Jennyt3]

Hi thank you for your reply!

No contract as such, but I do have in writing how much I would be paid. I don't send her invoices normally, most of the time she pays me in advance upon my acceptance of a project.

Thanks, Jennifer