Chaps, Iceman and all.
Certification of an aircraft is final. The FAA and EASA have certified the airbus 330 as a Category C aircraft. This cannot change because an operator decides to classify it as a CAT D aircraft for operational reasons.
The airlines in the fragrant harbour have categorised the aircraft as CAT C for straight in approaches and CAT D for circle to land.
This is because the speed during the circle to land at max landing weight with Auto-Thrust ON is on the threshold of CAT D speeds, while airbus have certified it as CAT C even for circling to land because they don/t need to use the A/THR ON. (5 Kts makes all the difference).
The airline in question operates the aircraft as a CAT C aircraft. Standard practice for EASA compliant countries.
I trust this makes sense and clarifies the difference between certification category and operational classification by an airline. The link I provided earlier has the certification categories of all airbus aircraft.
Iceman I do fly the 330/340