Sorry to hear your story.. I am a UX designer myself having about 7 years of experience, let me know if you want to chat.
Per your question. Unfortunately I have never used any of this services, I have heard ppl using upwork but didn’t know it was that bad. I would recommend you try LinkedIn again. Instead of posting a job, just search for product/UX designers as a role. And from the results, reaching out to any person with experiences close to what u need. Even tho their experience don’t align you can still reach out. Cuz a designer would definitely know more other designers who can help you out. I would also recommend to check out dribbble, since u only needed UI, just check people’s visual work and contact them from there. It maybe more efficient. Hope that helps.
Per your question. Unfortunately I have never used any of this services, I have heard ppl using upwork but didn’t know it was that bad. I would recommend you try LinkedIn again. Instead of posting a job, just search for product/UX designers as a role. And from the results, reaching out to any person with experiences close to what u need. Even tho their experience don’t align you can still reach out. Cuz a designer would definitely know more other designers who can help you out. I would also recommend to check out dribbble, since u only needed UI, just check people’s visual work and contact them from there. It maybe more efficient. Hope that helps.