My calls take longer, but I’m getting the complicated cases. How do I explain the numbers?

In our team review, my name was at the bottom of the chart for average call time. Our target is five minutes. Mine was nearly eight.

I work on a returns desk. During the past fortnight, the shift lead has sent me several calls where the order history was split between two systems or the customer had already contacted us twice. I like being trusted with those cases, but they don’t fit neatly into the comparison.

I also know some of my longer calls could be shorter. I spent too long explaining a form yesterday when I could have asked which box the customer was stuck on. I don’t want to use complexity as a blanket excuse.

The shift lead said, “We all get difficult calls.” I have the case notes but haven’t looked at anyone else’s assignments.

How would you raise the mismatch without sounding as though I want a separate standard? What evidence would help distinguish work I need to improve from work the chart hasn’t described?