Personally, if the product or service is late, and you havent told the customer it will be late (12days and counting in this case) no matter how big or small the order is, you should be WELL prepared to cop a fair slaging on the chin, and not chuck a sooky la la at the customer. You stay calm, explain the problem to them, appologise like nothing else, make them happy. Then hang up the phone and call them whatever you like really if you havent told them whats going on, it is bad customer service and you have asked for it. Even if they are spending only $10, you dont know how much they have to spend in years to come. End of it, no customers, no money, no money, no food.
That said, there are also ways of asking for things. There is no need to be rude to people. But still customers are who pay the bills, you do not piss them off.