Thanks all for the quick responses.

In my effort to be brief, I didn't explain the problem clearly. here are the details:

I booked (on phone with BA) a Prem Econ return between London and Chennai and at the same time upraded to Club using miles (25,000). I have flown the outbound sector and was due to use the inbound tomorrow. Unfortunately, my business commitments mean I have to delay the return until next week.
I contacted BA this morning to change the flight (the original Prem Econ was changeable for a fee) and they informed me that :
a) the flight I wanted is wide open
b) there would be a charge for the change (expected)
c) I would "forfeit" my miles.

This is a regular conversation for me with them and I asked as always,
i) why can you not credit the unused miles back (answer: rules)
ii) are there seats for mile upgrade available - (answer: yes, but you can't use them as your flight is part flown).

I do not understand the intention or `morality' of the policy - it really feels like theft. What is the point of a `loyalty' scheme which clearly favours casual px and holidaymakers who can predict accurately their travel rather than business travellers buying premium tickets and who pay for flexibility?

This is a regular accurance for me and has so far cost me over 100,000 in the last 12 months and I'm getting pretty fed up with it...