+1 ^ -- I also transferred a previously booked Celebrity cruise to Dave at TLC -- their offer was the best of any agency. TLC only deals with RCCL, Celebrity and Princess for now (I really hope they work with others soon), and I was very satisfied. There were no additional service charges, and I was still able to get my OBC from having booked onboard.

BTW - I may be wrong , but I think Cabin Clearance Store is the online-only agency of Cruise Brothers, as they are both located in the same town (also both use the same internet interface). The difference being that CCStore is very difficult to reach via phone --and no "hand-holding", you need to know exactly what you want to book. But their prices are very good if you have a little experience with cruising.