Just called and had a very surprising call -- frontline CSR did nothing but transferred me to a 'relationship manager', who read me the long spiel about the benefits, then offered me 1 bonus mile per dollar on gas, grocery, and utilities for the next 90 days, up to 8000 bonus miles. Asked for any other offers and there weren't any, so I accepted that.
She went to her manager to get approval or something, then came back and said she could ALSO waive the annual fee. Awesome.
This is my only Barclays card, it has a pathetically small limit, and I basically never use it.