It's been over a year that I have been purchasing BPCL fuel vouchers (from amex reward multiplier) and redeeming them across BPCL petrol pumps across NCR. All you have to do is go to the pump and say you want to redeem a "Fuel Voucher/FV". Redemption is done through a pinelab POS machine. I am yet to find one petrol pump that has refused the FV. Some employees may be ignorant and in rare occasions I have taken control over the POS and redeemed it myself - while teaching them how its done lol.
Usually in these cases petrol pumps redeem your fuel vouchers first and then fill the tank out of precaution.
By doing this i pay no fuel surcharge waiver, my 1500*4 spend target is met and i earn accelerated rewards on a spend that otherwise would accrue none!