I'm not sure I follow the OP. So you paid for excess luggage, checked-in and the flight was cancelled. You then rescheduled for a later flight, checked-in again.

I'm not sure if your complaint is that you were charged again for excess luggage? or Did you choose not to use your excess luggage allowance and as a result want a refund?

Edit: Having re-read the posts I think it is the latter. In which case I don't see why you should be refunded. You chose to take less luggage - end of story.