I currently have a TXL-AUH Air Berlin redemption booking for next year, which I'm looking to replace with a LHR-HKG 2-4-1 redemption [followed by a HKG-DXB/AUH leg].

I can only book the latter once the Avios from cancelling the former are recredited.

Does anybody know if I can cancel the Air Berlin redemption and book the 2-4-1 in the same transaction over the phone? And how much will it cost me?

Any experience of how I can do the HKG-DXB/AUH leg on Avios [assuming CX?] would also be gratefully received.