Gemini API Billing Spike ($213) – Google confirmed unauthorized usage but won't refund? Need advice.

Gemini API
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Hi everyone,

I’m facing a major billing issue with the Gemini API on Google Cloud and wanted to see if anyone has successfully navigated a refund for a security leak.

The Situation: On May 4th, my project had a massive billing spike of over $213 in just a few hours. I did a forensic audit and found something very suspicious:

  • Model Mismatch: My app (Flutter/Next.js) only uses gemini-2.5-flash for text. However, I was billed for Gemini 3.1 Flash Image and Gemini 2.5 Pro—models that aren’t even in my codebase.

  • High Volume: Traffic peaked at 8 requests per second. My app is a small tool for generating titles; it is physically impossible for users to trigger that volume.

  • Potential Leak: I suspect the key was extracted from a physical test device I lent out that was running the app in debug mode.

Support Response: I chatted with Google Billing Support. The agent confirmed that the charges were for models not used by my app and acknowledged it was an anomaly. However, they then said they “can’t issue a credit” and told me to dispute it with my bank (chargeback).

I’m hesitant to do a chargeback because I’ve heard Google might ban the entire billing account or workspace if you do that. I currently have an escalated email ticket open.