Well,
Upgrade Please, ... I'll take that as a compliment!
As it happens, I have in the past three days been looking at redemption flights on BA and, consequently, the associated charges. The surcharges were not fully detailed and I am not aware of any carrier that does. It is long overdue for them to be compelled to tell you the details, rather than just wrap them up into one line. As I recall, they WERE told yo detail them some years ago but that has fallen away. Anyone that knows the actual rules (UK) might want to start a new thread about that!
BA web site states:
Insurance and security surcharge rates
For tickets originating in UK a surcharge per person per BA sector or equivalent = £2.50
Fuel Surcharge per BA sector per person
The surcharge applies, as detailed below, to all tickets issued on or after 3 June 2008, based on the flight duration and where the ticket was purchased. The surcharge applies to all passengers, including children and infants, on international and domestic flights.
All long haul flights less than nine hours in duration = £78
All long haul flights more than nine hours in duration = £109
If you choose to pay using a UK billed credit card you will incur a credit card surcharge of £3.50 per ticket.
Tickets purchased in the UK for travel to Australia carry a surcharge of £129.50 per sector.
No explanation was given for this last item and, since it did not apply to my proposed booking, I did not pursue it. My cynical guess is that it is more fuel cost and tapping this busy and lucrative route.
Also, if you book on BA.com but do not live in the UK there is a further surcharge for the privilege.
Thus (for me): LHR-YVR in WTP cabin brought
£211.20 per seat and, having deducted the fuel and security, I was left with £99.70 of other charges that would include the UK departure tax and whatever BA can stuff into it. Naturally they CANNOT place any 'security' related charge in there as it has already been itemised at £2.50. (Yeah, right!)
Since carriers are won't to be (ahem) 'flexible' with these charges, I cross referenced them, preparing a 'booking' with the identical flight numbers and days but proposing to pay cash - to see if the charges changed. They did not.
I know from one attempt to use Air Miles (not BA Miles) but on a BA flight, the extra charges levied by Air Miles were higher than those levied by BA when I made a test of the identical flights and days. Air Miles would not explain to me what the breakdown of costs was.
In conclusion:-
1) Some carriers may inflate the charges for redemption flights but BA does not appear to do so. You can choose not to collect FFMs and not to use them. If you
do then it is their rule book.
2) It is generally accepted that the best value for FFMs is to use them to upgrade a booking to a higher cabin or pay part cash/part miles. Also, using FFMs for short and medium haul is not as good value as using them for long haul.