As an Expert, you'll undoubtedly receive some customer complaints. While many of our business partners already have macros that help address these issues, it's also helpful to remember that BLAST method for handling customer complaints.
B - Believe - Avoid becoming defensive with the customer; assume that what the customer is saying is fact (without admitting guilt or fault.) Your role in the interaction is as a problem solver, not an interrogator. A customer is only going to become more defensive and upset if they feel as if you're questioning the validity or truth of their complaint.
L - Listen - In our world, this means to Read. Instead of just sending a rebuttal, take time to understand what the customer is saying. Put yourself in their position and ask how you'd feel if you went through what they are describing.
A - Apologize - Tell the customer that you're sorry for the situation and that you understand how they must feel. An apology may not fully solve the problem, but it can go a long way toward defusing the situation. Often a customer just wants to know that their complaint was heard.
S - Satisfy - Do your best to satisfy the customer. You'll need to do this within the bounds of the policies for each business partner, but go out of your way to help the customer. Offer a return or partial refund, if that's an option. Perhaps you can send them a coupon to compensate for the experience that they had.
T - Thank - Spend some time thanking the customer for their business, for reaching out, and for helping improve the business. They could have easily aired this grievance to the world, or just stopped doing business with the business partner, but instead, they're working directly with the business partner to resolve the issue.
Following these steps will go a long way to ensuring a five-star customer review for you and the business partner.