Try Dolphin Marine Centre ( i think that is the name)... but they are definitely in Orana St Buddina, just off Pt Cartwright dve (at the roundabout entrance to the shopping centre).
I got mine serviced there for the 1st time (moved up from brissie). They seemed ok, with the normal prices.
If you know of a better one, please send me a pm, as my own is coming up for service in a few months again!
regards
Mike