Our MUC-LHR flight has been cancelled & we have been transferred to the next flight on same day. However, we would prefer an earlier flight as we will be connecting with BA15 to SYD.
I sent an email to a link that was provided, only to receive a generic reply that didn't change anything.
Manage My Booking doesn't give me access to change flights due to the fare class. It's still a long way off at this point.

Is there a possibility of getting the flight changed and who would I ring. I don't think there is an office here in AUS (maybe at the BA airport counter at SYD?).
The email also referred to an 'involuntary' refund. Should I just claim this and then book the earlier flight online, hopefully at the same cost.
thanks.