Companies can say that they won't have an actual human look into your issues, but there's a person that handles letters that might turn into lawsuits and other legal issues, and you can always ensure that they get contacted instead. Certified mail is pretty quick to write and costs like $3 to send, and you can look up the company's agent for service of process.

It might not do anything - writing a letter that sufficiently implies that you are actually collecting documentation and preparing for a lawsuit is an actual skill, and your demands may be unreasonable for them to handle - but you will get an actual factual human being to at least start reading what you've written. And as a bonus, their KPI is in terms of "number of incidents per year" rather than "number of resolved tickets per day".

I've not had much luck with that option, you need a large megaphone for it in most circumstances.

I've had better luck lately just using contact services to find the personal cellphone and email address of high-ranking employees and contacting them to get escalation.

You don't think that would automatically get shut down for spam-like activity?