I booked a ticket using Avios and cash (it was an avios booking with a partial payment in cash to reduce the amount of Avios required), It was booked through the Avios portal (it was not a cash booking with a reduction in price by paying, in part, with Avios).

The ticket cost 90,500 Avios miles plus $555 in cash.

I need to cancel (flight is not until summer 2025), and British Airways calculated the amount of the refund, but the refund amount they quoted is only $371 ($184 less than what I paid in cash) plus the 90,500 mileage refund. The agent explained that the way refunds are calculated can result in less cash than what I paid.

I thought that the only fee I would pay would be the $55 Avios cancellation fee (the reward flight originated in the US) and possibly a differential in currency conversion rates (but changes in currency conversion rates would not account for the extra $184 amount they want to deduct from the refund I am owed),.

Does this sound right? Are cash refund amounts less than what you pay in cash (for Avios plus cash bookings)?