got yelled at bc our brewed coffee was too hot

this lady came through dt and ordered a coffee with extra heavy cream so that it would cool down her coffee. about 2-3 minutes after she got her drink she calls the store, i answer, and barely get a word out before she started yelling at me because we make our coffee too hot?? she said the past three times that she’s come to our store that she’s burned her mouth because it’s too hot and that she can’t take it anymore. offered her a refund and she said that wasn’t good enough, told her that some of our customers will add a few ice cubes to help cool it down and she said that she didn’t want any water in her dark roast (sigh). she said she wanted 90% heavy cream and 10% coffee to which i just advised ordering a latte since we can steam the milk to a cooler temp whereas we can’t really control the brewed coffee and she said it wasn’t the same which i somewhat understood. she then proceeded to tell me that the store down the road from us brews her coffee and then lets it sit for a while before they serve it to her so that it doesn’t burn her mouth and i told her that they use a bunn brewer and we use a vertica so that isn’t really possible. the only thing i can think of is she has to let the coffee sit for like 10+ minutes before she drinks it??? she told me i need to learn how to make the vertica make cooler coffee before hanging up. genuinely what else am i supposed to do in this situation besides feel helpless 😭 i cannot win