I understand the most common reasons that may create conflict between VOC and VOB are:
1. Such demands of the customers which may go against the business laws / regulations or business as a whole.
2. Unawareness of the customer about the terms of the services
3. Lack of clarity on business practices i.e lack of transparency of business
4. Deals closed in a hurry without having properly understood the customer requirements
5. Ambiguity in internal processes of the company
The above reasons can create conflict between VOC and VOB.