I've supported a call center. We had specific escalation routes where problems could be sent to higher levels. The most obvious is the "I want to talk to your manager" escalation, but the agents, managers, and QC agents could push buttons that flagged additional review.
My advice for getting attention: don't be rude (EVERYONE is rude, this won't get any one's attention), be CLEAR about the problem AND solution, evoke emotion in the listener (remember, the listener is a QC person who reviews the call days later)
Try something like: I'm on vacation and my daughter was REALLY looking to see a musical. Do you have kids? Mine LOVE Beauty and the Beast - she has her backpack and t shirt, she is adorable. Every time we try to buy a ticket, it gets rejected. I think I forgot to notify you that I'm traveling. I'm so sorry - it just slipped my mind!
[1] https://www.hsbc.co.uk/help/security-centre/report-a-problem...
[I just learned that the FCC is considering not allowing calls made outside the US to be spoofed as numbers originating inside the US. I thought that was the whole point behind STIR/SHAKEN, silly me].
There's not really any alternative to calling a trusted number.
To be fair, I did because my card had been rejected literally 30 seconds before while trying to make a purchase. But it was only after the phone call ended that I realised what I had done. I phoned them back on a number listed on their website, asked them to confirm that I had indeed spoken with HSBC fraud detection, and they confirmed. I then lambasted them for asking me all the questions they tell their customers never to answer.
They're just training their customers to give out information, and even alert customers like myself can sometimes have a moment of panic and comply.