They should turn Clayton Street / Nun Street / Grainger Street / Newgate Street into a gyratory imo with all buses running around in a clockwise circle (I know slightly longer for buses heading towards High Level) with Grainger Street still being two way. Then turn Newgate / Nun / Clayton streets into bus stops. They're all wide enough for bays if you removed the taxi ranks, loading bays and parking and all could do with a boost in trade.

The taxi rank can be moved into the bus stop opposite of Sinners which is unused.