But this is just one way of using your cashback so you're effectively still GBP 875 out of pocket. If you channel your spending through the BMI Amex instead, and spend GBP 35,000 on BA tickets, then you will get 175,000 Avios (@ 5 Avios per GBP spent - at least in theory)... If you use the BA Amex, you will get 105,000 Avios (@ 3/1) plus a 2-4-1 voucher. You're free to do with them whatever you want... Am I missing something?