This rule identifies abnormal refund patterns that may indicate merchant fraud schemes, money laundering, or processing abuse.

System alerts when:
1. A merchant's refund/reversal rate exceeds 10% of total transactions
2. Calculated over a rolling 30-day window

Excessive refunds can indicate several fraud scenarios:
- Return fraud: Processing fake returns for cash/credit
- Money laundering: Using refunds to layer and move illicit funds
- Merchant collusion: Issuing fraudulent refunds to confederates
- Processing errors: Terminal misconfiguration or operator error
- Friendly fraud environment: Customers exploiting lenient return policies

This rule generates an ALERT (not automatic hold) to enable fraud analyst review while maintaining transaction flow for further investigation.