I understand how you feel...helpless and frustrated. When I had gastric sleeve surgery on 2/13/2014, it was in Tijuana (cost was less that $5,000 at the time)! This was because of insurance denying my initial attempt (I wasn't going to appeal since my health was in jeopardy. Now I need a revision to gastric bypass, I kinda expect the same response. Of course, now with COVID, Tijuana is high risk, if I was allowed to go and it was safe. But do not give up, nothing will change if you stop trying.
Pain stopped me from working in October 2018, and due to lots of meds, I have gained almost all the weight that I lost, and kept off over five years. I share your frustration-let's keep going until we get what we need!