You need to escalate this to the support tier where people are allowed to use their brains. Possibly writing to their legal department would do the trick?
> You want to communicate with the bank in a manner which suggests that you’re an organized professional who is capable of escalating the matter if the bank does not handle it themselves. [...] Mean words cannot hurt a bank. Threats cannot hurt a bank. Paper trails, though, are terrifying to regulated institutions. Your bank’s customer support representatives are taught to evaluate whether someone looks like they’re competent and collecting a paper trail. If they are, the CS rep is supposed to stop touching the case immediately and instead escalate them to a supervisor or to the legal department.