Contabo bandwidth bill way off—anyone else?

Contabo billed me 4.2TB overage for May. My own counters show 1.8TB total. As said, something is wrong.

To be honest, I did not notice at first—auto-pay. Then I checked because the amount seemed off.

My setup:

• 1x HostHatch VPS, 2TB included
• vnStat on host: 1.79TB combined in+out
• Contabo portal: 6.02TB "billable"
• Overage charge: €89.40

I opened ticket 6 days ago. No response yet. Before I escalate, I want to understand: how does Contabo measure? Is it 95th percentile? Is it layer-2 framing overhead? Something else? I cannot find methodology in their terms.

Has anyone else seen discrepancies this large?

I had something similar with RackNerd last year. Not this large but. They were counting internal traffic to their own object storage. Which should have been free. I only noticed because the bill jumped 300%. Took three weeks to resolve. They never explained why it started...