Same problem here in the States. Our categories are Delta (A), Charlie (B but with lights and sirens), and Alpha (C - nonemergency), and our computer-aided dispatch churns out more Charlie calls than anything. The vast majority are downgraded to Alpha five minutes in, or whenever the system controller thinks the crew might not make it in the required time. How many times have we run hot for a nursing home patient going for a PEG tube replacement? And yes, I've been to several Alpha calls that later became Priority-1 transports. Ah, computers...