That is SO frustrating and I feel your pain! My next idea would be next time you are on a help call, ask multiple times for someone from the Escalations Team to call you. (That's what the person referred to their team as when they reached out to me.) Although they asked me to walk through the issue again with a shared screen so they could see, they actually went beyond the script of "try a new browser" "try incognito" etc. and eventually found the issue (it did take several hours, most of it I was on hold while they poked around). I feel like they can maybe see more on the back end of your account than then the other support techs can, but I could be wrong about that. Good luck to you.