Get pretty firm but polite, and tell them you are not hanging up the call until it is resolved. You will eventually get someone who will see it through to the end for you.
The operators make up some blatant lies as to why you can't speak with a supervisor, or why they cant contact their "specialist" team at that moment. They will try anything to get you off the phone. Just say you are happy to wait, and will not hang up, even if it takes hours for them to get it resolved. But, they will probably just disconnect you whilst you are on hold anyway.
I eventually got someone who seemed to care and called back etc, and got it done.