Let's try to establish some facts about the problem.
Does the engine run hot when sitting in traffic or when on a run (40 MPH +), or both?
If it's got hot does a period of cruising at speed bring the temperature down again?
If you leave it idling at full working temperature for a few miuntes do both radiator hoses get piping hot? Do the fans come on periodically to control the coolant temperature? (try this with climate off, so the air con fans aren't running).
At speed, there is more than enough airflow through the radiator to keep the engine cool, so that takes the fans out of the equation and we are looking at a fault in the coolant circuit itself (thermostat, water pump, blocked radiator, airlock). If that lot is working but it gets hot in traffic, the fans and associated relays and thermoswitches come under scrutiny.
Gauges are not always accurate, as has been said. If the fans are coming on and off to control the temperature and it doesn't overheat on a run then all is well, IMHO.
Kevin