I got an update from British Airways, and I am passing this along (in case anyone encounters similar discrepancies) -

The agent clarified that the fee for cancellation (from the US) is $55 + $25 phone assistance fee. The agent said that the portion I paid in cash (to reduce the amount of Avois required for the 1 ticket) was non-refundable; there was an additional amount I paid for taxes, which is refundable. I didn't realize that the amount of cash paid to reduce the # of Avios for a ticket is nonrefundable. Passing it along, in case anyone opts to reduce the # of Avios required for a ticket by paying cash.