Dropshipping suppliers can make mistakes and when this happens it will be your name on the line. As the supplier is an invisible third party, you’ll need to own the blame when dealing with the customer. If the customer is unhappy, you can, for example, offer a free upgrade or refund the shipping cost, depending on the nature of the complaint. After the customer’s complaint has been addressed, you can then take it up with the supplier yourself. If mistakes happen regularly, find a new supplier.