Sorry this happened to you! Feel free to send me your case number (email in profile), and I'll escalate it. The Support personnel have hopefully been helping out, as all Billing Issues are covered regardless of support tier. I obviously don't know the ins and outs of payment instrument refunds / do debit cards mean that you actually do have to contact your bank, but I'm sure people in Support do.
I certainly don't think a student just learning the ins and outs of a cloud provider's services should be able to spend 10k+ without warnings/thresholds that require configuration to exceed. It would be positive for platform adoption to make that process better.