Data Point: I see an earlier post saying a $300+ avianca charge being declined. I asked for reimbursement for award ticket taxes/fees of $250 (high because it was through LHR). Agent asked what it was for, and when I said taxes he asked where the actual ticket charge was. I told him it was an award ticket and that LHR charges crazy taxes. There was also a $25 charge on the card for phone booking. But, approved in the end. I told him I'd send him the email receipt for the redemption if needed, but he was super helpful and reversed it right away.