renault megane 2006 fan / heater blower not working?

had this checked out and contacts cleaned etc . Worked for 2 days and then stopped. So motor seems Ok. TOld it could be resistor pack/harness that needs replaced (despite some forums saying that heater should work on setting 4 - mine DOESNT work on any setting !!) Anyway any tips would be useful to help diagnose problem and tips on how to get at the parts to fix eg remove panels /what the parts look like ! etc Thanks fo any help Trev