Its definitely a concern - who knows how many more threads have been removed (@curve_marie - willing to share any stats?)!
My experience is you can get things sorted, but you do have to be patient, assertive, able to deal with missing funds for weeks at a time and in extremis make it clear to Curve that you will take the issue to the Financial Ombudsman Service.
In both issues I’ve had, Curve have eventually (inadvertently, I presume) resolved things in my favour, so its not all bad! It is more than likely other people have given up and lost out.
Like you, I now only use it for small transactions. I’ve also stopped recommending it to friends, because I don’t want to feel like I’m responsible for someone being in the position @melanieparker found herself in.
Edit - by ‘in my favour’ I want to clarify that I ended up getting more back than I had lost, as opposed to simply getting things refunded correctly so everything balanced.