You need to analyze how often this happens and what the circumstances are, and then make your policy choice. I agree that you need to go one way or the other and be consistent about it. The last time I studied this, while we had this happen on an occasional basis, it wasn't more than three times on any one customer in a 12 month period. Your analysis may lead you to a different conclusion.
My opinions are not necessarily my employers.
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell